ROS1 and non-small cell lung carcinoma: The discovery of gene rearrangements between the echinoderm microtubule-associated protein-like 4 (EML4) gene and the ALK gene that lead to constitutive activation of ALK in NSCLC [109, 110] greatly contributed to the subsequent development and approval of crizotinib, a small-molecule inhibitor of ALK, c-ros oncogene 1 receptor tyrosine kinase (ROS1), and MET.