Furthermore, aiming to clarify the development of a normal counterpart and precancerous lesion of non-terminal respiratory unit (TRU) origin in lung adenocarcinomas, Koji Okudela et al. found that the expression of HNF4α was similar between bronchiolar metaplastic lesions and terminal bronchioles and that some of the metaplastic lesions exhibited an unequivocally higher frequency and expression level of HNF4α comparable to that observed in non-TRU lung adenocarcinomas48. The gene discussed is HNF4A; the disease is lung adenocarcinoma.