KRAS and colorectal carcinoma: Forty to forty-five percent of CRC are characterized by mutations in the KRAS proto-oncogene, most frequently affecting codons 12 (G12D, 13%; G12V, 9%) and 13 (G13D, 8%) of exon 2, which results in a constitutive activation of the EGFR pathway and induces a malignant transformation of the cell6.