Receptor tyrosine kinase which binds promiscuously transmembrane ephrin-B 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. Together with its cognate ligand/functional ligand EFNB2 is involved in the regulation of cell adhesion and cell migration, and plays a central role in heart morphogenesis, angiogenesis and blood vessel remodeling and permeability (PubMed:29444212). EPHB4-mediated forward signaling controls cellular repulsion and segregation from EFNB2-expressing cells (By similarity) (PubMed:29444212). Involved in somitogenesis (PubMed:9765210). ATP + L-tyrosyl-[protein] = ADP + H(+) + O-phospho-L-tyrosyl-[protein] Morpholino knockdown of the protein results in marked vascular anomalies of the dorsal cranial vessels including both dorsal longitudinal and mesencephalic veins. Belongs to the protein kinase superfamily. Tyr protein kinase family. Ephrin receptor subfamily.