In the sentence extracted from biomedical literature, identify all the disease entities. The required answer format is the same sentence with HTML <span> tags to mark up specific entities. 
### Entity Markup Guides:
Use <span class="disease"> to denote a disease.

### Input Text: The DPC4 gene , which is located at 18q21 , has been identified as a tumor - suppressor gene from examination of pancreatic cancers .
### Output Text:
The DPC4 gene , which is located at 18q21 , has been identified as a tumor - suppressor gene from examination of <span class="disease">pancreatic cancers</span> . 