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: Chemical cystitis was induced by cyclophosphamide ( CYP ) which is metabolized to acrolein , an irritant eliminated in the urine .
### Output Text:
Chemical cystitis was induced by <span class="chemical">cyclophosphamide</span> ( <span class="chemical">CYP</span> ) which is metabolized to <span class="chemical">acrolein</span> , an irritant eliminated in the urine . 