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: Tissues were analyzed at 0 , 5 , 7 , 11 , 21 , 45 , 80 and 126 days after PAN injection so as to include both the acute phase of proteinuria associated with foot process effacement ( days 5 - 11 ) and the chronic phase of proteinuria associated with glomerulosclerosis ( days 45 - 126 ) .
### Output Text:
Tissues were analyzed at 0 , 5 , 7 , 11 , 21 , 45 , 80 and 126 days after <span class="chemical">PAN</span> injection so as to include both the acute phase of proteinuria associated with foot process effacement ( days 5 - 11 ) and the chronic phase of proteinuria associated with glomerulosclerosis ( days 45 - 126 ) . 