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: Finally , we identified the localization of proliferating cell nuclear antigen - positive , ED - 1 - positive , and terminal dUTP nick - end labeled - positive cells in the hypoxic cortical area in the remnant kidney model .
### Output Text:
Finally , we identified the localization of proliferating cell nuclear antigen - positive , ED - 1 - positive , and terminal dUTP nick - end labeled - positive cells in the hypoxic cortical area in the remnant kidney model . 