The prevalent and best-characterized modalities for eliminating cancer cells are the directed secretion of lytic granules containing pro-apoptotic granzymes and pore-forming perforin, as well as expression of death receptor ligands such as TNF-related apoptosis-inducing ligand (TRAIL) and Fas ligand, which can trigger caspase-dependent apoptosis in target cells expressing the cognate receptors (24–26). The gene discussed is PRF1; the disease is cancer.