Receptor tyrosine kinase which binds promiscuously membrane-bound ephrin-A family ligands residing on adjacent cells, leading to contact-dependent bidirectional signaling into neighboring cells. The signaling pathway downstream of the receptor is referred to as forward signaling while the signaling pathway downstream of the ephrin ligand is referred to as reverse signaling. Binds with a low affinity EFNA3 and EFNA4 and with a high affinity to EFNA1 which most probably constitutes its cognate/functional ligand. Upon activation by EFNA1 induces cell attachment to the extracellular matrix inhibiting cell spreading and motility through regulation of ILK and downstream RHOA and RAC. Plays also a role in angiogenesis and regulates cell proliferation. May play a role in apoptosis.Hirai H., Science 238:1717-1720(1987).Owshalimpur D., Mol. Cell. Probes 13:169-173(1999).Hillier L.W., Nature 424:157-164(2003).