Tyro3 (Tyrosine-protein kinase receptor TYRO3) is a 890-amino acid protein (~98kDa) is a tyrosine-protein kinase. It belongs to the A, Xenopus/Amphibian,l/Tyro3 family of receptor tyrosine kinases, which also includes A, Xenopus/Amphibian,l and Mer. Gas6 (growth arrest-specific gene-6) is a ligand for all members of the A, Xenopus/Amphibian,l family and they play essential roles in spermatogenesis, immunoregulation and phagocytosis. Tyro3 is e, Xenopus/Amphibian,pressed at high levels during postnatal development and in the adult in the corte, Xenopus/Amphibian,. Tyro3 and Gas6 have neurotrophic roles in the nervous system. In addition, the signalling interactions of A, Xenopus/Amphibian,l and Tyro3 may play roles in tumourigenesis, inflammation as well as other cell proliferative diseases.