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: Our report may show an adverse effect on the Rho / ROCK pathway by sorafenib use .
### Output Text:
Our report may show an adverse effect on the Rho / ROCK pathway by <span class="chemical">sorafenib</span> use . 