TNFSF4 and Autoimmunity: The tumor necrosis factor ligand superfamily member 4 (TNFSF4, OX40L) encodes a type II transmembrane protein which can interact with TNFRSF4 (OX40) leading to a costimulatory signal for various immune responses, and which has been put forward as a potential therapeutic target to control autoimmunity [44].