PROM1 and colorectal cancer: Previous studies showed that CD133 was expressed on cancer cells but not haemocytes [4, 5] and most carcinoma cells expressed a membrane glycoprotein EpCAM [34], which is considered as one of CSC markers in several carcinoma types [37].We found that CD133 was expressed on EpCAM+ cells (Fig 4), indicating those CD133 expressing cells are colorectal cancer cells.