GJA1 and neoplasm: Although ectopic Cx43 expression does not increase basal GJ dye transfer between mural cells and endothelial cells, mural cells nucleofected with a wild-type Cx43 expression plasmid retain functional gap junctions with endothelial cells despite the presence of tumor media (Fig. 5a; Cx43 Mock vs. Cx43 231, p = 0.908, ns).