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: Her red blood cells ( RBCs ) had increased incubated Heinz body formation , decreased reduced glutathione ( GSH ) , and decreased GSH stability .
### Output Text:
Her red blood cells ( RBCs ) had increased incubated Heinz body formation , decreased reduced <span class="chemical">glutathione</span> ( <span class="chemical">GSH</span> ) , and decreased <span class="chemical">GSH</span> stability . 