NTRK1 and adenocarcinoma: Previous large-scale mutational profiling studies of lung cancer have examined either only the exons encoding the activation loops of receptor tyrosine kinase (RTK) genes (47 of 58 RTK genes) in 119 primary NSCLCs, of which 70 (59%) were lung adenocarcinomas [4], or the coding sequences of 518 protein kinases in a relatively limited number of samples, i.e. 26 primary lung neoplasms (7 adenocarcinomas) and seven cancer cell lines (6 adenocarcinomas) [32].