The expression of CSC markers CD44, CD133, and CD166 were significantly induced by the two gene mutations although KRas mutation alone did not6 as previously reported that expression of a mutant KRas allele alone in mouse colonic cells failed to expand the stem cell population.42 Therefore, loss-of-APC is required for the mutant KRAS-induced CSC activation, and these results confirmed by critical enhancement of the spheroid forming ability of the CRC cells carrying both of the two gene mutations. Here, KRAS is linked to colorectal carcinoma.