Adhesive molecules of the endothelial cell-cell junction. The vascular permeability barrier is maintained by tight junctions comprised of claudins, occludins, and JAMs, followed by adherens junctions comprised primarily of vascular endothelial cadherin (VE-cadherin) associated with the actin cytoskeleton via members of the catenin family. Underneath these specialized compartments lies the most abundant endothelial cell surface receptor, PECAM-1, which is expressed at 1–2 x 106 molecules per cell. Figure adapted from E. Dejana, Nature Reviews Molecular Biology 5:261, 2004 (69).