as of december 31 , 2014 , our operations have been funded primarily by $ 105.1 million in equity investments from venture investors , $ 219.3 million from public investors , $ 64.2 million in equity investments from our collaboration partners and $ 216.8 million in upfront payments , milestones , and net research and development payments from our collaboration partners . we estimate that we have spent approximately $ 122.3 million on research and development for the three year period from 2012 through 2014. we expect to continue to incur significant expenses and increasing operating losses over at least the next several years . we expect our expenses will increase substantially in connection with our ongoing activities , as we : conduct clinical trials for dalantercept and ace-083 ; 63 continue our preclinical studies and potential clinical development efforts of our existing preclinical therapeutic candidates ; continue research activities for the discovery of new therapeutic candidates ; manufacture therapeutic candidates for our preclinical studies and clinical trials ; seek regulatory approval for our therapeutic candidates ; and operate as a public company . we will not generate revenue from product sales unless and until we or a partner successfully complete development and obtain regulatory approval for one or more of our therapeutic candidates , which we expect will take a number of years and is subject to significant uncertainty . all current and future development and commercialization costs for sotatercept and luspatercept are paid by celgene . if we obtain regulatory approval for dalantercept , ace-083 or any future therapeutic candidate , we expect to incur significant commercialization expenses related to product sales , marketing , manufacturing and distribution to the extent that such costs are not paid by future partners . we will seek to fund our operations through the sale of equity , debt financings or other sources , including potential additional collaborations . however , we may be unable to raise additional funds or enter into such other arrangements when needed on favorable terms , or at all . if we fail to raise capital or enter into such other arrangements as , and when , needed , we may have to significantly delay , scale back or discontinue the development or commercialization of one or more of our therapeutic candidates . our ability to generate product revenue and become profitable depends upon our and our partners ' ability to successfully commercialize products . we expect to incur losses for the foreseeable future , and we expect these losses to increase as we continue our development of , and seek regulatory approvals for , our therapeutic candidates and potentially begin to commercialize any approved products . for a description of the numerous risks and uncertainties associated with product development , see `` risk factors `` . financial operations overview revenue collaboration revenue we have not generated any revenue from the sale of products . our revenue to date has been predominantly derived from collaboration revenue , which includes license and milestone revenues and cost sharing revenue , generated through collaboration and license agreements with partners for the development and commercialization of our therapeutic candidates . cost sharing revenue represents amounts reimbursed by our collaboration partners for expenses incurred by us for research and development activities and , potentially , co-promotion activities , under our collaboration agreements . cost sharing revenue is recognized in the period that the related activities are performed . to the extent that we reimburse collaborators for costs incurred in connection with activities performed by them , we record these costs as a reduction of cost-sharing revenue . contract manufacturing revenue we have generated contract manufacturing revenue in the past but have no current contract manufacturing arrangements . contract manufacturing revenue consists of revenue received for producing bulk drug substance for third parties other than our partners . costs and expenses research and development expenses research and development expenses consist primarily of costs directly incurred by us for the development of our therapeutic candidates , which include : direct employee-related expenses , including salaries , benefits , travel and stock-based compensation expense of our research and development personnel ; expenses incurred under agreements with clinical research organizations , or cros , and investigative sites that will conduct our clinical trials ; 64 the cost of acquiring and manufacturing preclinical and clinical study materials and developing manufacturing processes ; allocated facilities , depreciation , and other expenses , which include rent and maintenance of facilities , insurance and other supplies ; expenses associated with obtaining and maintaining patents ; and costs associated with preclinical activities and regulatory compliance . research and development costs are expensed as incurred . costs for certain development activities are recognized based on an evaluation of the progress to completion of specific tasks using information and data provided to us by our vendors and our clinical sites . we can not determine with certainty the duration and completion costs of the current or future clinical trials of our therapeutic candidates or if , when , or to what extent we will generate revenues from the commercialization and sale of any of our therapeutic candidates for which we or any partner obtain regulatory approval . we or our partners may never succeed in achieving regulatory approval for any of our therapeutic candidates . the duration , costs and timing of clinical trials and development of our therapeutic candidates will depend on a variety of factors , including : the scope , rate of progress , and expense of our ongoing , as well as any additional , clinical trials and other research and development activities ; future clinical trial results ; potential changes in government regulation ; and the timing and receipt of any regulatory approvals . story_separator_special_tag we determine the estimates of clinical activities incurred at the end of each reporting period through discussion with internal personnel and outside service providers as to the progress or stage of completion of trials or services , as of the end of each reporting period , pursuant to contracts with numerous clinical trial centers and cros and the agreed upon fee to be paid for such services . the significant factors considered in estimating accruals include the number of patients enrolled and the percentage of work completed to date . costs of setting up clinical trial sites for participation in the trials that are paid for in advance are expensed over the estimated set-up period . while the set-up periods vary from one arrangement to another , such set-up periods generally take approximately three months . set-up activities include clinical site identification , institutional review board , or irb , submissions , regulatory submissions , clinical investigator kick-off meetings and pre-study site visits . clinical trial site costs related to patient enrollments are accrued as patients are entered into the trial . stock-based compensation we account for our stock-based awards in accordance with asc topic 718 , compensation—stock compensation , or asc 718 , which requires all stock-based payments to employees , including grants of employee stock options and modifications to existing stock options , to be recognized in the statements of operations and comprehensive income ( loss ) based on their fair values . we recognize the compensation cost of awards subject to service-based vesting conditions over the requisite service period , which is generally equal to the vesting term . for awards subject to both performance and service-based vesting conditions , we recognize compensation cost using an accelerated recognition method when it is probable that the performance condition will be achieved . we account for stock-based awards to non-employees using the fair value method . stock options granted to non-employees are subject to periodic revaluation over their vesting terms and stock-based compensation cost is recognized using an accelerated recognition method . we estimate the fair value of our stock-based awards to employees and non-employees using the black-scholes option pricing model , which requires the input of highly subjective assumptions , including ( 1 ) the expected volatility of our stock , ( 2 ) the expected term of the award , ( 3 ) the risk-free interest rate and ( 4 ) expected dividends . due to the lack of a public market for our common stock prior to the completion of our initial public offering in september 2013 , and resulting lack of company-specific historical and implied volatility data , we have based our estimate of expected volatility on the historical volatility of a group of similar companies that are publicly traded . for these analyses , we have selected companies with characteristics that we believe are comparable to ours , including enterprise value , risk profiles , position within the industry , and with historical share price information sufficient to meet the expected life of the stock-based awards . we compute the historical volatility data using the daily closing prices for the selected companies ' shares during the equivalent period as the calculated expected term of our stock-based awards . we will continue to apply this process until a sufficient amount of historical information regarding the volatility of our own stock price becomes available . we have estimated the expected life of our employee stock options using the `` simplified `` method , whereby , the expected life equals the average of the vesting term and the original contractual term of the option . the risk-free interest rates for periods within the expected life of the option are based on the u.s. treasury yield curve in effect during the period the options were granted . we also estimate forfeitures at the time of grant , and revise those estimates in subsequent periods if actual forfeitures differ from estimates . we use historical data to estimate pre-vesting option forfeitures to the extent that actual forfeitures differ from our estimates , the difference is recorded as a cumulative adjustment in the period the estimates were revised . stock-based compensation expense recognized in the consolidated financial statements is based on awards that are ultimately expected to vest . for the years ended december 31 , 2014 , 2013 and 2012 , we used a forfeiture rate of 4 % , 4 % , and 5 % , respectively . stock-based compensation totaled approximately $ 4.8 million , $ 2.2 million , and $ 1.2 million for the years ended december 31 , 2014 , 2013 and 2012 , respectively . we expect the impact of our stock-based compensation expense for stock-based awards granted to employees and non-employees to grow in future periods due to the potential increases in the value of our common stock and headcount . warrants to purchase preferred stock and common stock as of december 31 , 2014 , we had warrants outstanding to purchase 422,104 shares of common stock , of which warrants to purchase 409,470 shares of our common stock contain a provision requiring an adjustment to the number of shares in the event we issue common stock , or securities convertible into or exercisable for common stock , at a price per share lower than the warrant exercise price . the anti-dilution feature requires the warrants to be classified as liabilities and measured at fair value , with changes in fair value recognized as a component of other income ( expense ) . the fair value of the warrants to 69 purchase common stock on the date of issuance and on each re-measurement date for those warrants to purchase common stock classified as liabilities was estimated using either the monte carlo simulation framework , which incorporates future financing events over the remaining life of the warrants to purchase common stock , or for certain re-measurement dates including december 31 , 2013 and 2014

net cash used in operating activities was $ 53.2 million for the year ended december 31 , 2014 , and consisted primarily of a net loss of $ 51.3 million adjusted for non-cash items including a decrease in fair value of warrants of $ 5.0 million , stock-based compensation expense of $ 4.8 million , depreciation and amortization of $ 1.1 million , payments of deferred interest of $ 0.5 million , and a net decrease due to changes in operating assets and liabilities of $ 2.3 million . the significant items in the change in operating assets and liabilities include a decrease in deferred revenue of $ 1.7 million for the celgene collaboration . other components of the change in operating assets and liabilities include a decrease in collaboration receivables of $ 0.2 million , a decrease in deferred rent of $ 0.5 million , a decrease in accounts payable of $ 0.2 million , and an increase in prepaid and other current assets of $ 0.3 million . net cash used in operating activities was $ 19.6 million for the year ended december 31 , 2013 , and consisted primarily of a net loss of $ 21.9 million adjusted for non-cash items including an increase in fair value of warrants of $ 26.9 million , stock-based compensation expense of $ 2.2 million , depreciation and amortization of $ 0.9 million , forgiveness of the related party receivable of $ 0.2 million , accretion of deferred interest of $ 0.3 million , and amortization of deferred debt issuance costs of $ 0.2 million , and a net decrease due to changes in operating assets and liabilities of $ 28.5 million .


 Write a concise suspicious activity report of the following text delimited by triple backquotes. Return your response as a formal report which covers the key points highlighting the location,dates,entity names and account holder information in chronological order of the text.
     ```net cash used in operating activities was $ 53.2 million for the year ended december 31 , 2014 , and consisted primarily of a net loss of $ 51.3 million adjusted for non-cash items including a decrease in fair value of warrants of $ 5.0 million , stock-based compensation expense of $ 4.8 million , depreciation and amortization of $ 1.1 million , payments of deferred interest of $ 0.5 million , and a net decrease due to changes in operating assets and liabilities of $ 2.3 million . the significant items in the change in operating assets and liabilities include a decrease in deferred revenue of $ 1.7 million for the celgene collaboration . other components of the change in operating assets and liabilities include a decrease in collaboration receivables of $ 0.2 million , a decrease in deferred rent of $ 0.5 million , a decrease in accounts payable of $ 0.2 million , and an increase in prepaid and other current assets of $ 0.3 million . net cash used in operating activities was $ 19.6 million for the year ended december 31 , 2013 , and consisted primarily of a net loss of $ 21.9 million adjusted for non-cash items including an increase in fair value of warrants of $ 26.9 million , stock-based compensation expense of $ 2.2 million , depreciation and amortization of $ 0.9 million , forgiveness of the related party receivable of $ 0.2 million , accretion of deferred interest of $ 0.3 million , and amortization of deferred debt issuance costs of $ 0.2 million , and a net decrease due to changes in operating assets and liabilities of $ 28.5 million .
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 Suspicious Activity Report : as of december 31 , 2014 , our operations have been funded primarily by $ 105.1 million in equity investments from venture investors , $ 219.3 million from public investors , $ 64.2 million in equity investments from our collaboration partners and $ 216.8 million in upfront payments , milestones , and net research and development payments from our collaboration partners . we estimate that we have spent approximately $ 122.3 million on research and development for the three year period from 2012 through 2014. we expect to continue to incur significant expenses and increasing operating losses over at least the next several years . we expect our expenses will increase substantially in connection with our ongoing activities , as we : conduct clinical trials for dalantercept and ace-083 ; 63 continue our preclinical studies and potential clinical development efforts of our existing preclinical therapeutic candidates ; continue research activities for the discovery of new therapeutic candidates ; manufacture therapeutic candidates for our preclinical studies and clinical trials ; seek regulatory approval for our therapeutic candidates ; and operate as a public company . we will not generate revenue from product sales unless and until we or a partner successfully complete development and obtain regulatory approval for one or more of our therapeutic candidates , which we expect will take a number of years and is subject to significant uncertainty . all current and future development and commercialization costs for sotatercept and luspatercept are paid by celgene . if we obtain regulatory approval for dalantercept , ace-083 or any future therapeutic candidate , we expect to incur significant commercialization expenses related to product sales , marketing , manufacturing and distribution to the extent that such costs are not paid by future partners . we will seek to fund our operations through the sale of equity , debt financings or other sources , including potential additional collaborations . however , we may be unable to raise additional funds or enter into such other arrangements when needed on favorable terms , or at all . if we fail to raise capital or enter into such other arrangements as , and when , needed , we may have to significantly delay , scale back or discontinue the development or commercialization of one or more of our therapeutic candidates . our ability to generate product revenue and become profitable depends upon our and our partners ' ability to successfully commercialize products . we expect to incur losses for the foreseeable future , and we expect these losses to increase as we continue our development of , and seek regulatory approvals for , our therapeutic candidates and potentially begin to commercialize any approved products . for a description of the numerous risks and uncertainties associated with product development , see `` risk factors `` . financial operations overview revenue collaboration revenue we have not generated any revenue from the sale of products . our revenue to date has been predominantly derived from collaboration revenue , which includes license and milestone revenues and cost sharing revenue , generated through collaboration and license agreements with partners for the development and commercialization of our therapeutic candidates . cost sharing revenue represents amounts reimbursed by our collaboration partners for expenses incurred by us for research and development activities and , potentially , co-promotion activities , under our collaboration agreements . cost sharing revenue is recognized in the period that the related activities are performed . to the extent that we reimburse collaborators for costs incurred in connection with activities performed by them , we record these costs as a reduction of cost-sharing revenue . contract manufacturing revenue we have generated contract manufacturing revenue in the past but have no current contract manufacturing arrangements . contract manufacturing revenue consists of revenue received for producing bulk drug substance for third parties other than our partners . costs and expenses research and development expenses research and development expenses consist primarily of costs directly incurred by us for the development of our therapeutic candidates , which include : direct employee-related expenses , including salaries , benefits , travel and stock-based compensation expense of our research and development personnel ; expenses incurred under agreements with clinical research organizations , or cros , and investigative sites that will conduct our clinical trials ; 64 the cost of acquiring and manufacturing preclinical and clinical study materials and developing manufacturing processes ; allocated facilities , depreciation , and other expenses , which include rent and maintenance of facilities , insurance and other supplies ; expenses associated with obtaining and maintaining patents ; and costs associated with preclinical activities and regulatory compliance . research and development costs are expensed as incurred . costs for certain development activities are recognized based on an evaluation of the progress to completion of specific tasks using information and data provided to us by our vendors and our clinical sites . we can not determine with certainty the duration and completion costs of the current or future clinical trials of our therapeutic candidates or if , when , or to what extent we will generate revenues from the commercialization and sale of any of our therapeutic candidates for which we or any partner obtain regulatory approval . we or our partners may never succeed in achieving regulatory approval for any of our therapeutic candidates . the duration , costs and timing of clinical trials and development of our therapeutic candidates will depend on a variety of factors , including : the scope , rate of progress , and expense of our ongoing , as well as any additional , clinical trials and other research and development activities ; future clinical trial results ; potential changes in government regulation ; and the timing and receipt of any regulatory approvals . story_separator_special_tag we determine the estimates of clinical activities incurred at the end of each reporting period through discussion with internal personnel and outside service providers as to the progress or stage of completion of trials or services , as of the end of each reporting period , pursuant to contracts with numerous clinical trial centers and cros and the agreed upon fee to be paid for such services . the significant factors considered in estimating accruals include the number of patients enrolled and the percentage of work completed to date . costs of setting up clinical trial sites for participation in the trials that are paid for in advance are expensed over the estimated set-up period . while the set-up periods vary from one arrangement to another , such set-up periods generally take approximately three months . set-up activities include clinical site identification , institutional review board , or irb , submissions , regulatory submissions , clinical investigator kick-off meetings and pre-study site visits . clinical trial site costs related to patient enrollments are accrued as patients are entered into the trial . stock-based compensation we account for our stock-based awards in accordance with asc topic 718 , compensation—stock compensation , or asc 718 , which requires all stock-based payments to employees , including grants of employee stock options and modifications to existing stock options , to be recognized in the statements of operations and comprehensive income ( loss ) based on their fair values . we recognize the compensation cost of awards subject to service-based vesting conditions over the requisite service period , which is generally equal to the vesting term . for awards subject to both performance and service-based vesting conditions , we recognize compensation cost using an accelerated recognition method when it is probable that the performance condition will be achieved . we account for stock-based awards to non-employees using the fair value method . stock options granted to non-employees are subject to periodic revaluation over their vesting terms and stock-based compensation cost is recognized using an accelerated recognition method . we estimate the fair value of our stock-based awards to employees and non-employees using the black-scholes option pricing model , which requires the input of highly subjective assumptions , including ( 1 ) the expected volatility of our stock , ( 2 ) the expected term of the award , ( 3 ) the risk-free interest rate and ( 4 ) expected dividends . due to the lack of a public market for our common stock prior to the completion of our initial public offering in september 2013 , and resulting lack of company-specific historical and implied volatility data , we have based our estimate of expected volatility on the historical volatility of a group of similar companies that are publicly traded . for these analyses , we have selected companies with characteristics that we believe are comparable to ours , including enterprise value , risk profiles , position within the industry , and with historical share price information sufficient to meet the expected life of the stock-based awards . we compute the historical volatility data using the daily closing prices for the selected companies ' shares during the equivalent period as the calculated expected term of our stock-based awards . we will continue to apply this process until a sufficient amount of historical information regarding the volatility of our own stock price becomes available . we have estimated the expected life of our employee stock options using the `` simplified `` method , whereby , the expected life equals the average of the vesting term and the original contractual term of the option . the risk-free interest rates for periods within the expected life of the option are based on the u.s. treasury yield curve in effect during the period the options were granted . we also estimate forfeitures at the time of grant , and revise those estimates in subsequent periods if actual forfeitures differ from estimates . we use historical data to estimate pre-vesting option forfeitures to the extent that actual forfeitures differ from our estimates , the difference is recorded as a cumulative adjustment in the period the estimates were revised . stock-based compensation expense recognized in the consolidated financial statements is based on awards that are ultimately expected to vest . for the years ended december 31 , 2014 , 2013 and 2012 , we used a forfeiture rate of 4 % , 4 % , and 5 % , respectively . stock-based compensation totaled approximately $ 4.8 million , $ 2.2 million , and $ 1.2 million for the years ended december 31 , 2014 , 2013 and 2012 , respectively . we expect the impact of our stock-based compensation expense for stock-based awards granted to employees and non-employees to grow in future periods due to the potential increases in the value of our common stock and headcount . warrants to purchase preferred stock and common stock as of december 31 , 2014 , we had warrants outstanding to purchase 422,104 shares of common stock , of which warrants to purchase 409,470 shares of our common stock contain a provision requiring an adjustment to the number of shares in the event we issue common stock , or securities convertible into or exercisable for common stock , at a price per share lower than the warrant exercise price . the anti-dilution feature requires the warrants to be classified as liabilities and measured at fair value , with changes in fair value recognized as a component of other income ( expense ) . the fair value of the warrants to 69 purchase common stock on the date of issuance and on each re-measurement date for those warrants to purchase common stock classified as liabilities was estimated using either the monte carlo simulation framework , which incorporates future financing events over the remaining life of the warrants to purchase common stock , or for certain re-measurement dates including december 31 , 2013 and 2014

