MSN and non-small cell lung carcinoma: In NSCLC, the most common ROS1 fusion partner is CD74. Less common partners include SDC4, EZR, SLC34A2, TPM3, LIMA1, and MSN. The ROS1 proto-oncogene has been identified to be translocated in NSCLC with a frequency of 1.7% (18/107) to 2.6% (17/656)9,10.