May play an important role in neural organelle transport, and in transduction of nerve signals or in nerve growth (PubMed:12445626, PubMed:16527258, PubMed:16696124, PubMed:9191101). May play a role in neurite extension (PubMed:26430118). Expressed predominantly in brain. Also weakly expressed in lung and spleen. In brain, expressed strongly in nerve fibers of the cerebral cortex, anterior cerebral nuclei, hypothalamus, amygdaloid complex, brain stem of the metaencephalon and medulla oblongata, and moderately expressed in soma of neurons of the dentate gyrus of the hippocampus and Purkinje cells of the cerebellum. Expression is developmentally regulated as axonal fibers innervate, extend collateral fibers and finally attain a stable state. First detected at postnatal day 6 in cell bodies and apical dendrites of pyramidal neurons in the developing cerebral cortex, with expression gradually increasing during postnatal development. In P1 retina, strongly expressed in the optic nerve fiber layer, and weakly expressed in ganglion cells, presumptive amacrine and horizontal cells. At P10, also strongly expressed in other parts of the retina such as the ganglion cells, inner plexiform layer and horizontal cells. Expression decreases as the retina develops further to maturity. By retinoic acid in neuroblastoma Neuro2a cells. Down-regulated following fear conditioning (at protein level) (PubMed:26430118). Belongs to the VMP family.