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: In contrast , mPGES - 1 - / - mice were largely resistant to lithium - induced polyuria and a urine concentrating defect , accompanied by nearly complete blockade of high urine PGE ( 2 ) and cAMP output .
### Output Text:
In contrast , mPGES - 1 - / - mice were largely resistant to <span class="chemical">lithium</span> - induced polyuria and a urine concentrating defect , accompanied by nearly complete blockade of high urine <span class="chemical">PGE ( 2 )</span> and cAMP output . 