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: In vitro characterization of parasympathetic and sympathetic responses in cyclophosphamide - induced cystitis in the rat .
### Output Text:
In vitro characterization of parasympathetic and sympathetic responses in <span class="chemical">cyclophosphamide</span> - induced cystitis in the rat . 