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: GLEPP1 receptor tyrosine phosphatase ( Ptpro ) in rat PAN nephrosis .
### Output Text:
GLEPP1 receptor <span class="chemical">tyrosine</span> phosphatase ( Ptpro ) in rat <span class="chemical">PAN</span> nephrosis . 