Plays a critical role in endothelial cell capillary morphogenesis. Interacts with NID1. May interact with CTTN. Localized predominantly at the tight junctions of vascular endothelial cells and to a lesser extent at the luminal surface of vascular endothelial cells. Detected in endothelial cells from colorectal cancer, and in endothelial cells from primary cancers of the lung, liver, pancreas, breast and brain. Not detectable in endothelial cells from normal tissue. Expressed in fibrovascular membrane with increased expression in individuals with proliferative diabetic retinopathy. N-glycosylated. Belongs to the plexin family.