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: NIK - 247 , tacrine and E - 2020 all strongly inhibited acetylcholinesterase ( AChE ) in human red blood cells ( IC50s = 1 . 0 x 10 ( - 6 ) , 2 . 9 x 10 ( - 7 ) and 3 . 7 x 10 ( - 8 ) M , respectively ) .
### Output Text:
<span class="chemical">NIK - 247</span> , <span class="chemical">tacrine</span> and <span class="chemical">E - 2020</span> all strongly inhibited acetylcholinesterase ( AChE ) in human red blood cells ( IC50s = 1 . 0 x 10 ( - 6 ) , 2 . 9 x 10 ( - 7 ) and 3 . 7 x 10 ( - 8 ) M , respectively ) . 