Source:http://linkedlifedata.com/resource/umls/id/C0079973
NCI: p21 K-RAS protein is encoded by the K-RAS gene. Two KRAS isoforms are produced by alternative splicing. RAS proteins are involved in transmembrane signal transduction as monomeric GTP-binding proteins, with intrinsic GTPase activity, that alternate between an inactive GDP-bound form and an active GTP-bound form. RAS proteins are activated by a guanine nucleotide-exchange factor and inactivated by a GTPase-activating protein. Mitogen-stimulated RAS enhances MYC accumulation by stabilizing MYC protein. This stabilization is dependent on the RAS/RAF/MAPK pathway, which appears to inhibit the proteasome-dependent degradation of MYC. Mutations of specific amino acids activate c-RAS to transform cells and are implicated in a variety of human tumors. KRAS is involved in malignancy much more often than is HRAS. (from OMIM 190070, SWISS-PROT P01116, P01118, and NCI)