Ephrin type-A receptor 4(EPHA4) belongs to the protein kinase superfamily and Ephrin receptor subfamily. EPHA4 contains 1 Eph LBD domain, 2 fibronectin type-III domains, 1 protein kinase domain and 1 SAM domain. EPH and EPH-related receptors have been implicated in mediating developmental events, particularly in the nervous system. Receptors in the EPH subfamily typically have a single kinase domain and an extracellular region containing a Cys-rich domain and 2 fibronectin type III repeats. The ephrin receptors are divided into 2 groups based on the similarity of their extracellular domain sequences and their affinities for binding ephrin-A and ephrin-B ligands.