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: This response was restricted to the striatum and contrasted sharply with unresponsive eGFP - microglia in surrounding brain areas that are not damaged by METH .
### Output Text:
This response was restricted to the striatum and contrasted sharply with unresponsive eGFP - microglia in surrounding brain areas that are not damaged by <span class="chemical">METH</span> . 