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: CONCLUSIONS : Azathioprine triggers suicidal erythrocyte death , an effect presumably contributing to azathioprine - induced anemia .
### Output Text:
CONCLUSIONS : <span class="chemical">Azathioprine</span> triggers suicidal erythrocyte death , an effect presumably contributing to <span class="chemical">azathioprine</span> - induced anemia . 