CD44 and colorectal cancer: Flow cytometry and immunocytochemistry analysis (Figure 1C,D) showed that radiation increased the expression of CD133 and ALDH in all colorectal cancer cells except LoVo cells with unchanged expression of CD133, whereas CD44 expression was selectively increased in radioresistant colorectal cancer cells such as HCT116, DLD1, and HT29 (Figure 1C).