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: Heavy proteinuria was common after the use of SRL as rescue therapy for renal transplantation .
### Output Text:
Heavy proteinuria was common after the use of <span class="chemical">SRL</span> as rescue therapy for renal transplantation . 