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: Complete disappearance of the tumor was induced with 1 . 0 mg doxorubicin / kg .
### Output Text:
Complete disappearance of the tumor was induced with 1 . 0 mg <span class="chemical">doxorubicin</span> / kg . 