Examples include the selection of RAS mutant clones in colorectal cancer treated with EGFR antibodies, such as cetuximab or panitumumab,11 or the acquisition of a secondary EGFR T790M kinase domain mutation mediating resistance to EGFR kinase inhibitors, such as gefitinib or erlotinib in non–small-cell lung cancer.12,13. This evidence concerns the gene EGFR and colorectal cancer.