Apart from EGFR and KRAS, the proto-oncogene B-Raf (BRAF) gene that encodes a serine/threonine kinase was identified in 3% (18/687) of western patients with lung adenocarcinomas (72) but only in 0.5% (25/5,125) of Asian patients (64). The gene discussed is MARK2; the disease is lung adenocarcinoma.