TNF is known to promote opening of the endothelial pannexin 1 (Panx1) membrane channel, allowing for ATP release, associated with inflammatory cell recruitment. However, there is evidence that Panx1 may be involved in the regulation of cellular inflammatory responses independent of direct ATP signalling, although the pathways have not been elucidated. We therefore examined Panx1 for roles in the control of cytokine release in human endothelial cells following treatment with TNF.