Members of this RTK family represented a novel structural motif, when sequenced. The ligands for this family, growth arrest specific protein 6 (GAS6, Q14393) and protein S (PROS1, P07225), are secreted plasma proteins which undergo vitamin K-dependent post-translational modifications generating carboxyglutamate-rich domains which are able to bind to negatively-charged surfaces of apoptotic cells.

AXL tyrosine kinase inhibitors have been described [1].

1. Mollard A, Warner SL, Call LT, Wade ML, Bearss JJ, Verma A, Sharma S, Vankayalapati H, Bearss DJ. (2011) Design, Synthesis and Biological Evaluation of a Series of Novel Axl Kinase Inhibitors. ACS Med Chem Lett, 2 (12): 907-912. [PMID:22247788]

2. Nagata K, Ohashi K, Nakano T, Arita H, Zong C, Hanafusa H, Mizuno K. (1996) Identification of the product of growth arrest-specific gene 6 as a common ligand for Axl, Sky, and Mer receptor tyrosine kinases. J Biol Chem, 271 (47): 30022-7. [PMID:8939948]

3. Stitt TN, Conn G, Gore M, Lai C, Bruno J, Radziejewski C, Mattsson K, Fisher J, Gies DR, Jones PF. (1995) The anticoagulation factor protein S and its relative, Gas6, are ligands for the Tyro 3/Axl family of receptor tyrosine kinases. Cell, 80 (4): 661-70. [PMID:7867073]