ALK and non-small cell lung carcinoma: In NSCLC, kinase genes, such as ALK, ROS1, RET, NTRK1, and NTRK3 [but also BRAF, MET, EGFR, and fibroblast growth factor receptor (FGFR)] or other proto-oncogenes such as neuregulin 1 (NRG1), may all be subject to gene rearrangements that lead to constitutive downstream pathway activation (3, 6, 11, 43–45).