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 mean protective effect by adding monoHER before DOX led to a significant 4 . 4 - fold reduction ( P < 0 . 001 , 95 % CI 2 . 3 - 8 . 2 ) of abnormal cardiomyocytes .
### Output Text:
The mean protective effect by adding <span class="chemical">monoHER</span> before <span class="chemical">DOX</span> led to a significant 4 . 4 - fold reduction ( P < 0 . 001 , 95 % CI 2 . 3 - 8 . 2 ) of abnormal cardiomyocytes . 