LIGHT, also known as TNFSF14, CD258 and HVEM-L, is a type II transmembrane protein belonging to the TNF family of ligands. It is produced by activated T-cells and signals via the lymphotoxin beta receptor (LTbetaR) and the herpes virus entry mediator (HVEM). It is a potent initiator of T cell co-stimulation signals that play a role in tumor and allograft rejection. LIGHT is reported to work together with IFN-g to activate caspase activity, resulting in cleavage of Bcl-2.