KRAS is a RAS/MAPK signaling pathway GTPase that is involved in the control of cell proliferation. It is the most commonly mutated oncogene in human cancers, with a high frequency in carcinomas of the pancreas, colon, and lung. KRAS mutation is commonly associated with poor prognosis and resistance to therapy. The four somatic KRAS mutations with the most frequency in tumors, G12D, G12V, G12C and G13D, are associated with a large number of morphological and regulatory changes and a sudden increase in the rate of cellular proliferation. These mutations are driving events in the formation of invasive carcinomas when combined with the loss of function of a tumor suppressor such as APC. The protein is widely expressed, with cytoplasmic and/or membranous localization. References: Trends in Cancer 2017 3(10):686; Cold Spring Harb Perspect Med 2018 8(9):a031435; Stolze, 2015; Pino, 2010; Morkel ,2015