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: Chronic FK506 nephropathy consisted of rough and foamy tubular vacuolization ( 5 biopsies ) , arteriolopathy ( angiodegeneration of the arteriolar wall ; 20 biopsies ) , focal segmental glomerulosclerosis ( 4 biopsies ) and the striped form of interstitial fibrosis ( 11 biopsies ) .
### Output Text:
Chronic <span class="chemical">FK506</span> nephropathy consisted of rough and foamy tubular vacuolization ( 5 biopsies ) , arteriolopathy ( angiodegeneration of the arteriolar wall ; 20 biopsies ) , focal segmental glomerulosclerosis ( 4 biopsies ) and the striped form of interstitial fibrosis ( 11 biopsies ) . 