Although they were not identified in the present study, ALK fusion genes have been detected in mucinous adenocarcinomas [42], but are TTF-1-positive TRU-type adenocarcinomas with a mucinous morphology, a distinct entity from HNF4α-positive mucinous lung adenocarcinomas, exhibiting gastrointestinal features. Here, HNF4A is linked to mucinous adenocarcinoma.