ROS1 gene rearrangements lead to fusion of the entire tyrosine kinase domain of ROS1 with 1 of 12 different partners, including fusions with: TPM3, SDC4, SLC34A2, CD74 and EZR. ROS1gene rearrangements are present in about 1% of lung cancers where they are therapeutic targets for an FDA-approved agent Crizotinib. The gene discussed is ROS1; the disease is lung cancer.