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: AQP2 and UT - A1 expression was lowered in 6 week lithium - treated WT animals whereas in treated PKCa KO mice , AQP2 was only reduced by 2 - fold and UT - A1 expression was unaffected .
### Output Text:
AQP2 and UT - A1 expression was lowered in 6 week <span class="chemical">lithium</span> - treated WT animals whereas in treated PKCa KO mice , AQP2 was only reduced by 2 - fold and UT - A1 expression was unaffected . 