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: Additionally , since membrane leakage is a final stage of cytotoxicity , the disruption of the structural characteristics of biomembranes by TAM may contribute to the multiple mechanisms of its anticancer action .
### Output Text:
Additionally , since membrane leakage is a final stage of cytotoxicity , the disruption of the structural characteristics of biomembranes by <span class="chemical">TAM</span> may contribute to the multiple mechanisms of its anticancer action . 