To explore how different mutations change the response of tumor cells to drugs we treated CaCO2 (wildtype for BRAF and KRAS), HCT116 (KRASG13D), and HT29 (BRAFV600E) colon carcinoma cells with the MEK inhibitor AZD6244 or with the RAF inhibitor Sorafenib for various periods of time. The gene discussed is KRAS; the disease is colon carcinoma.