While the ability to downregulate mural cell Cx43 is restricted to highly aggressive MDA-MB-231 and MDA-MB-468 cell lines in our study, we cannot preclude the possibility that other tumor cells may functionally inactivate Cx43 gap junctions by other means such as phosphorylation or altered Cx43 localization, which can be regulated by different mechanisms. This evidence concerns the gene GJA1 and neoplasm.