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 most patients , discontinuation of sirolimus resulted in a decrease , but not resolution , of proteinuria .
### Output Text:
In most patients , discontinuation of <span class="chemical">sirolimus</span> resulted in a decrease , but not resolution , of proteinuria . 