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: The present results are consistent with the carcinogenicity experiment suggesting that different mechanisms are involved in FANFT carcinogenesis in the bladder and forestomach , and that aspirin ' s effect on FANFT in the forestomach is not due to an irritant effect associated with increased cell proliferation .
### Output Text:
The present results are consistent with the carcinogenicity experiment suggesting that different mechanisms are involved in <span class="chemical">FANFT</span> carcinogenesis in the bladder and forestomach , and that <span class="chemical">aspirin</span> ' s effect on <span class="chemical">FANFT</span> in the forestomach is not due to an irritant effect associated with increased cell proliferation . 