It has previously been reported that the subset of patients with NSCLC, predominantly those with adenocarcinomas, possess a specific activating mutation in the epidermal growth factor receptor (EGFR) gene, which correlates with marked clinical responsiveness to the EGFR tyrosine kinase inhibitors, gefitinib or erlotinib (22–24). The gene discussed is EGFR; the disease is adenocarcinoma.