Background: We have shown before that Cx43 modulates the motility of HeLa cells and of endothelial precursor cells in a channel independent manner but the underlying mechanisms are unknown. Here we tested whether a potential candidate protein, cortactin, which stabilizes actin networks and regulates cell movement, interacts with Cx43. Methods: HeLa cells stably transfected with Cx43 or Cx43 mutants either encoding the N-terminal (AA 1-257) or the C-terminal part (AA 257-382) both tagged with GFP were used to perform immunoprecipitation (IP) experiments of Cx43 with cortactin. Channel function was measured by the gap junctional transfer of Calcein using FACS analysis (n=4). Cell motility was assessed by boyden chambers and by time-lapse microscopy using wound assay chambers. Results: IP experiments (n=3) yielded an interaction of full length Cx43 and the C-terminal part of Cx43 (without channel function) but not of the N-terminal part of Cx43 with cortactin. Since we found an inhibition of cell migration of 30% by inhibition of MAPK p38 activation, we analysed whether the interaction of Cx43 with cortactin is dependent on the activation of p38 which in turn mediates actin reorganization and cell migration. Inhibition of p38 activation by a specific inhibitor did not affect the interaction of Cx43 with cortactin (n=4). Conclusion: These results show that the gap junction protein Cx43 interacts with its C-terminal part with the actin binding protein cortactin and that this binding is independent of p38 activation. Further analyses are necessary to clarify whether this interaction plays a role in regulating cell movement or stabilizing actin networks.