AXL: AXL receptor tyrosine kinase, also known as UFO, JTK11. Entrez Protein NP_001690. It is a member of the receptor tyrosine kinase subfamily. Although it is similar to other receptor tyrosine kinases, this protein represents a unique structure of the extracellular region that juxtaposes IgL and FNIII repeats. It transduces signals from the extracellular matrix into the cytoplasm by binding growth factors like vitamin K-dependent protein growth-arrest-specific gene 6. It is involved in the stimulation of cell proliferation and can also mediate cell aggregation by homophilic binding. Alternatively spliced transcript variants encoding different isoforms have been identified.