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EPHB1A gene on chromosome 3q21-q23 that encodes a member of the ephrin-B receptor subfamily of receptor tyrosine kinases, which “promiscuously” bind membrane-bound ephrin-B family ligands residing on adjacent cells, leading to contact-dependent bidirectional signalling into neighbouring cells. EPHB1 regulates retinal axon guidance, ipsilaterally redirecting ventrotemporal retinal ganglion cells axons at the optic chiasm midline during nervous system development, a process that is thought to require repulsive interaction with EFNB2. In the adult nervous system, EPHB1 and EFNB3 regulate chemotaxis, proliferation and polarity of the hippocampus neural progenitors.
In addition to its role in axon guidance, EPHB1 also plays a key redundant role with other ephrin-B receptors in development and maturation of dendritic spines and synapse formation. It may also regulate angiogenesis and play a role in targeted cell migration by activating the MAPK/ERK cascade, and in adhesion by activating the JNK signalling cascade. EPHB1’s cognate/functional ephrin ligands include EFNB1, EFNB2 and EFNB3.