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: Somatic alterations of the DPC4 gene in human colorectal cancers in vivo .
### Output Text:
Somatic alterations of the DPC4 gene in human <span class="disease">colorectal cancers</span> in vivo . 