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 rats with PAN nephropathy , administration of rhIGF - I increased IGF - I and GH receptor gene expression , without altering the steady state level of IGF - I receptor mRNA .
### Output Text:
In rats with <span class="chemical">PAN</span> nephropathy , administration of rhIGF - I increased IGF - I and GH receptor gene expression , without altering the steady state level of IGF - I receptor mRNA . 