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: We describe 3 episodes of microangiopathic hemolytic anemia ( MAHA ) in 2 solid organ recipients under FK506 ( tacrolimus ) therapy .
### Output Text:
We describe 3 episodes of microangiopathic hemolytic anemia ( MAHA ) in 2 solid organ recipients under <span class="chemical">FK506</span> ( <span class="chemical">tacrolimus</span> ) therapy . 