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: To investigate how GAP43 expression ( GAP43 - ir ) correlates with MFS , we assessed the intensity ( densitometry ) and extension ( width ) of GAP43 - ir in the inner molecular layer of the dentate gyrus ( IML ) of rats subject to status epilepticus induced by pilocarpine ( Pilo ) , previously injected or not with cycloheximide ( CHX ) , which has been shown to inhibit MFS .
### Output Text:
To investigate how GAP43 expression ( GAP43 - ir ) correlates with MFS , we assessed the intensity ( densitometry ) and extension ( width ) of GAP43 - ir in the inner molecular layer of the dentate gyrus ( IML ) of rats subject to status epilepticus induced by <span class="chemical">pilocarpine</span> ( <span class="chemical">Pilo</span> ) , previously injected or not with <span class="chemical">cycloheximide</span> ( <span class="chemical">CHX</span> ) , which has been shown to inhibit MFS . 