To investigate the mechanism of resistance to cetuximab in colon cancer cells, we first tested the effect of cetuximab on cell proliferation and basal MET and SRC protein expression and phosphorylation in seven colon cancer cell lines, including three mutant KRAS lines (SW480, HCT-116, DLD-1) and four wild-type KRAS lines (HT-29, RKO, Caco-2 and DiFi). This evidence concerns the gene KRAS and malignant colon neoplasm.