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: Furthermore , reduction of ER stress in the TM with sodium 4 - phenylbutyrate prevented dexamethasone - induced ocular hypertension in WT mice .
### Output Text:
Furthermore , reduction of ER stress in the TM with <span class="chemical">sodium 4 - phenylbutyrate</span> prevented <span class="chemical">dexamethasone</span> - induced ocular hypertension in WT mice . 