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: We investigated whether the expression of the DCC protein in tumor cells is a prognostic marker in colorectal carcinoma .
### Output Text:
We investigated whether the expression of the DCC protein in <span class="disease">tumor</span> cells is a prognostic marker in <span class="disease">colorectal carcinoma</span> . 