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: These results suggest that the nephrotoxic effects of CsA and FK506 is likely mediated through binding to renal immunophilin and inhibiting calcineurin phosphatase .
### Output Text:
These results suggest that the nephrotoxic effects of <span class="chemical">CsA</span> and <span class="chemical">FK506</span> is likely mediated through binding to renal immunophilin and inhibiting calcineurin phosphatase . 