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 protein abundance of alpha - ENaC and beta - ENaC was increased in the inner stripe of the outer medulla ( ISOM ) and in the inner medulla ( IM ) but was not altered in the cortex .
### Output Text:
The protein abundance of alpha - ENaC and beta - ENaC was increased in the inner stripe of the outer medulla ( ISOM ) and in the inner medulla ( IM ) but was not altered in the cortex . 