Non-small cell lung cancer (NSCLC) with activating mutations in the epidermal growth factor receptor (EGFR) such as an exon 19 deletion and L858R mutation responds to first- and second-generation EGFR-tyrosine kinase inhibitors (EGFR-TKIs), including gefitinib, erlotinib, and afatinib1–4. The gene discussed is EGFR; the disease is non-small cell lung carcinoma.