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: Antitumor effect , cardiotoxicity , and nephrotoxicity of doxorubicin in the IgM solid immunocytoma - bearing LOU / M / WSL rat .
### Output Text:
Antitumor effect , cardiotoxicity , and nephrotoxicity of <span class="chemical">doxorubicin</span> in the IgM solid immunocytoma - bearing LOU / M / WSL rat . 