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: Hemolysis of human erythrocytes induced by tamoxifen is related to disruption of membrane structure .
### Output Text:
Hemolysis of human erythrocytes induced by <span class="chemical">tamoxifen</span> is related to disruption of membrane structure . 