GJA4 and neoplasm: Although a tumor-induced decrease in Cx37 in vSMC was also detected, previous reports indicate that heterocellular junctions between vascular endothelial cells and mural cells are composed primarily of mural cell Cx43 [9] and endothelial Cx43/40 [19], with limited presence of Cx37 at heterocellular junctions in the microvasculature [19, 20].