KRAS and adenoma: If one compares the above-mentioned mutation frequencies in sporadic CRC with the mutation frequencies of APC, K-Ras, B-Raf and CTNNB1 in serrated lesions and traditional adenomas in this study, it is evident that the mutation frequency along the serrated carcinogenesis pathway increases in the case of APC, remains basically unaltered in the case of K-Ras as well as CTNNB1 and decreases in the case of B-Raf.