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 the kidney , high levels of immunoreactive and enzymatically active calcineurin were found which were inhibited by the immunosuppressants CsA and FK506 , but not by rapamycin .
### Output Text:
In the kidney , high levels of immunoreactive and enzymatically active calcineurin were found which were inhibited by the immunosuppressants <span class="chemical">CsA</span> and <span class="chemical">FK506</span> , but not by <span class="chemical">rapamycin</span> . 