KRAS and colorectal cancer: To test this principle, we firstly examined the pERK1/2 and phenotypic response to Selumetinib in colorectal cancer cell lines that have known sensitivity differences when exposed to the agent for prolonged periods; RKO (BRAF mutant) and HRT18 (KRAS mutant) that are resistant and HCT116 (KRAS mutant) that is sensitive20,32.