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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.
ELKEars–nose and throat, lungs, kidneys An acronym for the organs involved in Wegener's granulomatosis–WG; limited WG spares the kidneys and lacks signs of systemic vasculitis; generalized WG involves the kidneys and/or has signs of systemic vasculitis; disease exacerbation is best monitored by measuring titers of antineutrophil cytoplasmic antibodies by indirect immunofluorescence. See Wegener's granulomatosis.
a large deer; there are two species, the European elk (Alces alces) and the American moose (A. americana). The largest deer, 6 ft high at the withers and 2000 lb in weight, with a prominent Roman nose, an overhanging upper lip and a beard hanging from the lower jaw, brown body hair and white on the legs. The bulls have palmate antlers, the cows have no antlers.
a blemish in a horse, a heavy, overhanging top lip.