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: It is concluded that PAP formation , in vivo , accounts , at least in part , for APAP - induced renal tubular necrosis .
### Output Text:
It is concluded that <span class="chemical">PAP</span> formation , in vivo , accounts , at least in part , for <span class="chemical">APAP</span> - induced renal tubular necrosis . 