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: The serum creatinine levels of patients in the mild - type chronic FK506 nephropathy group , which included 7 episode biopsies , were statistically higher than those in the minimum - type chronic FK506 - nephropathy group ( P < 0 . 001 ) .
### Output Text:
The serum <span class="chemical">creatinine</span> levels of patients in the mild - type chronic <span class="chemical">FK506</span> nephropathy group , which included 7 episode biopsies , were statistically higher than those in the minimum - type chronic <span class="chemical">FK506</span> - nephropathy group ( P < 0 . 001 ) . 