We also demonstrate that miR-5096 transfer via gap junctions is time-dependent. Both the GJIC and underlying Cx43 expression were transiently increased in transfected U87. After a few days in culture, gap junctions between U87 and HMEC have lost their functionality but miR-5096 is still transferred from U87 to HMEC, although less efficiently, suggesting that another still unidentified pathway is activated [27, 28]. Conversely, transfection of miR-5096 into HMEC does not affect the homocellular GJIC in HMEC monolayers (see Supplementary Figure S2), indicating that overexpression of miR differentially regulates Cx43 expression in HMEC and U87 [14, 29, 30].