KRAS and colorectal carcinoma: Further genetic mutations are needed in order to develop CRC, such as oncogenic K-ras activating mutations in the adenomatous stage, and eventually, deletion of chromosome 18q with inactivation of tumor-suppressor SMAD genes (SMAD2–SMAD4) and inactivation of the tumor-suppressor gene TP53 on chromosome 17p [54,55].