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: Interestingly , estradiol also induced PRL - R , SOCS - 3 , and CIS mRNA levels independently .
### Output Text:
Interestingly , <span class="chemical">estradiol</span> also induced PRL - R , SOCS - 3 , and CIS mRNA levels independently . 