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 kinin B2 receptor has been associated with the inflammation process , as well as the regulation of cytokine expression , and its deletion resulted in an improvement in the diabetic nephropathy status .
### Output Text:
The kinin B2 receptor has been associated with the inflammation process , as well as the regulation of cytokine expression , and its deletion resulted in an improvement in the diabetic nephropathy status . 