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: Furthermore , these data suggest an explanation as to how p53 inhibition can result in cardioprotection during drug treatment and , paradoxically , enhanced cardiotoxicity long after the cessation of drug treatment .
### Output Text:
Furthermore , these data suggest an explanation as to how p53 inhibition can result in cardioprotection during drug treatment and , paradoxically , enhanced cardiotoxicity long after the cessation of drug treatment . 