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: Furthermore , endogenous VEGF mRNA levels were suppressed in permanent RCC cell lines expressing wt - VHL , and nuclear run - on studies indicated that VHL regulation of VEGF occurs at least partly at the transcriptional level .
### Output Text:
Furthermore , endogenous VEGF mRNA levels were suppressed in permanent <span class="disease">RCC</span> cell lines expressing wt - VHL , and nuclear run - on studies indicated that VHL regulation of VEGF occurs at least partly at the transcriptional level . 