Plays a role in cell adhesion, and in cohesion of the endothelial monolayer at intercellular junctions in vascular tissue. Its expression may allow melanoma cells to interact with cellular elements of the vascular system, thereby enhancing hematogeneous tumor spread. Could be an adhesion molecule active in neural crest cells during embryonic development. Acts as surface receptor that triggers tyrosine phosphorylation of FYN and PTK2/FAK1, and a transient increase in the intracellular calcium concentration (By similarity). Detected at the surface of the cell body of motor neurons. Detected in lung, uterus and placenta (at protein level). Detected in heart, lung, kidney, adrenal gland, intestine, testis, skeletal muscle and aorta. Detected at low levels in adult brain, in particular in brain stem and spinal cord, but also in hippocampus, olfactory bulb and striatum (at protein level). Detected at high levels in brain throughout embryonic development (at protein level). Levels are lower in neonates and decrease during the first days after birth (at protein level).