Recombinant human ROS1 (ROS proto-oncogene 1), encompassing amino acids 1883-2347 (end) that contain the tyrosine kinase domain. The N-terminal end of this construct contains a GST-tag followed by a His-tag (6xHis), linked to the protein via a linker that includes a thrombin cleavage site, allowing removal of the tags from the protein if desired. The protein was affinity purified.