For example, mutations of tyrosine kinase signaling pathway genes, including EGFR(1–3), ALK(4), RET(5,6) and erbB2(7), are common in adenocarcinomas, whereas mutations of the nuclear factor erythroid 2-related 2 (NEF2L2; also known as NRF2) gene are characteristic of squamous cell carcinoma (8–10). This evidence concerns the gene ERBB2 and adenocarcinoma.