The Ptf1a-Cre , mir-17~92flox , LSL-KrasG12D , and Trp53flox  mouse strains have been described previously. Health status of all animals was monitored at least three times per week, and animals were euthanized when they displayed signs of distress or high tumor burden. Animals were maintained in specific pathogen-free facilities with abundant food and water. Mice were randomly assigned to the studies. Group sizes were estimated based on investigators’ prior experience. Euthanized mice that did not have pancreatic tumors were censored from the analysis. Mice of both genders were used in all studies. The pathologist was blinded to mouse genotypes for quantification of histopathologic lesions. All animal experiments were reviewed and approved by the University of Massachusetts Medical School Institutional Animal Care and Use Committee.