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: Clinical use of the anthracycline doxorubicin ( DOX ) is limited by its cardiotoxic effects , which are attributed to the induction of apoptosis .
### Output Text:
Clinical use of the <span class="chemical">anthracycline</span> <span class="chemical">doxorubicin</span> ( <span class="chemical">DOX</span> ) is limited by its cardiotoxic effects , which are attributed to the induction of apoptosis . 