In the presence of the gap junctional blocker, diapedesis efficiencies were significantly reduced in both the control HBL100v cells and the Cx43 expressing HBL100 cells (HBL100Cx43) (Fig. 6b), suggesting gap junctional coupling between the adjacent endothelial cells is important in regulating tumor cell diapedesis efficiency regardless of their connexin content. This evidence concerns the gene GJA1 and neoplasm.