PROM1 and colorectal cancer: CD133 was markedly expressed in Caco-2 (98%), HCT116 (83%), and HT29 (78%) cells, whereas SW480 and DLD1 showed low expression of CD133 (8% and 12%, respectively), indicating that the expression of CD44 was not strongly correlated with the expression of CD133 marker proteins in human colorectal cancer cell lines.