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: Confocal analyses demonstrated that pericellular p75 ( NTR ) - IR was not colocalized with the glial marker , glial fibrillary acidic protein ( GFAP ) .
### Output Text:
Confocal analyses demonstrated that pericellular p75 ( NTR ) - IR was not colocalized with the glial marker , glial fibrillary acidic protein ( GFAP ) . 