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: Erythropoietin restores the anemia - induced reduction in cyclophosphamide cytotoxicity in rat tumors .
### Output Text:
Erythropoietin restores the anemia - induced reduction in <span class="chemical">cyclophosphamide</span> cytotoxicity in rat tumors . 