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 change in GAP43 - ir present in Pilo - treated animals was a thinning of the band to a very narrow layer just above the granule cell layer that is likely to be associated with the loss of hilar cell projections that express GAP - 43 .
### Output Text:
The change in GAP43 - ir present in <span class="chemical">Pilo</span> - treated animals was a thinning of the band to a very narrow layer just above the granule cell layer that is likely to be associated with the loss of hilar cell projections that express GAP - 43 . 