KRAS and colorectal carcinoma: Cetuximab is effective in killing cells with wild-type KRAS, but not mutant KRAS. Using DiFi and Lim1215 CRC cell lines which both overexpress EGFR but are wild-type for KRAS, Misale et al. demonstrated that continuous cetuximab administration resulted in resistance of the cell lines to cetuximab over time [41].