Next to the important prediction of drug response for metastatic colorectal carcinomas, KRAS mutations may also be decisive for drug decision in NSCLC in regard to Erlotinib or Gefitinib, because these kinase inhibitors seem to be ineffective in carcinomas with KRAS mutation [12, 16, 17]. The gene discussed is KRAS; the disease is non-small cell lung carcinoma.