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: Increased ED - 1 , MAP kinases and NF - kappaB staining were also observed in the renal cortex from all gentamicin - treated rats compared to control ( p < 0 . 05 ) .
### Output Text:
Increased ED - 1 , MAP kinases and NF - kappaB staining were also observed in the renal cortex from all <span class="chemical">gentamicin</span> - treated rats compared to control ( p < 0 . 05 ) . 