ALK and non-small cell lung carcinoma: Interestingly, NSCLC gene rearrangements involving RET are mutually exclusive with other procarcinogenic driver mutations, eg. ALK or ROS1 rearrangements.57, 89, 90 Multiple fusion partners with RET have been described: According to a global registry where patients with RET‐rearranged NSCLC were involved, it was reported that among 81 cases with identified RET‐fusion partners, the kinesin family 5B gene (KIF5B) was involved in 72%.