CD44 and colonic neoplasm: Nowadays, the extensively used method to isolate or enrich colon cancer stem cells is cell sorting based on cell surface markers, such as CD133, Musasai-1, CD44, EpCAM, Lgr5, etc. Ricci-Vitiani L et al. reported the CD133+ cells which accounts for about 2.5% of the tumour cells are tumorgenic cells in colon cancer [33].