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: Proteinuria appeared in all series , but was 2 - 5 times more intense ( p > 0 . 001 ) and prolonged after doxorubicin treatment ( 400 - 700 mg / day ) , without significant difference between DXNP and DX .
### Output Text:
Proteinuria appeared in all series , but was 2 - 5 times more intense ( p > 0 . 001 ) and prolonged after <span class="chemical">doxorubicin</span> treatment ( 400 - 700 mg / day ) , without significant difference between DXNP and <span class="chemical">DX</span> . 