Amongst the currently accessible drugs against lung cancer, gefitinib (Iressa) and erlotinib (Tarceva), so called EGF receptor tyrosine kinase inhibitors (EGFR-TKIs), are effective in patients with EGFR mutations, including exon 19 deletion and exon 21 substitution (L858R) [5]. The gene discussed is EGFR; the disease is lung cancer.