EPCAM and renal cell carcinoma: Clear cell RCC, the most common type of RCC show differentiation to renal tubular epithelium histologically, but unlike normal tubular epithelium, the clear cell RCCs express vimentin and CK47, and this feature suggest stem cell differentiation or EMT in RCC, resulting in major limitation for CTC detection in RCC patients by current EpCAM-dependent CTC analysis method.