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: The ability of cardiomyocytes to synthesize DNA in response to experimentally induced cardiac hypertrophy was assessed in adult mice .
### Output Text:
The ability of cardiomyocytes to synthesize DNA in response to experimentally induced cardiac hypertrophy was assessed in adult mice . 