KRAS and hepatocellular carcinoma: Although ras proto-oncogenes produced by mutations in codons 12, 13, and 61 do not play major roles in hepatocellular carcinogenesis [15], abnormal activation of the RAS pathway occurs in human HCC, and activated (GTP-bound) Pan-RAS, HRAS, KRAS, and NRAS are significantly up-regulated in human hepatocarcinogenesis [16, 17].