FAS and nasopharyngeal carcinoma: Since caspase-8 can be activated after binding of death ligands TRAIL (tumor necrosis factor-related apoptosis inducing ligand) or FASLG (Fas ligand) to their respective receptors TRAIL-R1 and 2 and FAS [27], we were interested whether the TRAIL- and FASLG-signaling pathways were functional in NPC cells.