In the sentence extracted from biomedical literature, identify all the chemical entities. The required answer format is the same sentence with HTML <span> tags to mark up specific entities. 
### Entity Markup Guides:
Use <span class="chemical"> to denote a chemical.

### Input Text: In this study , we have utilized a rat model of progressive doxorubicin ( DOX ) - induced cardiomyopathy , applying multiple approaches , including cardiac magnetic resonance imaging ( MRI ) , to provide the most comprehensive characterization to date of the timecourse of serological , pathological , and functional events underlying this toxicity .
### Output Text:
In this study , we have utilized a rat model of progressive <span class="chemical">doxorubicin</span> ( <span class="chemical">DOX</span> ) - induced cardiomyopathy , applying multiple approaches , including cardiac magnetic resonance imaging ( MRI ) , to provide the most comprehensive characterization to date of the timecourse of serological , pathological , and functional events underlying this toxicity . 