Here, they recognise tumour cells expressing cognate antigens and initiate a cascade of effector functions, including the release of cytotoxic granules containing perforin and granzymes, as well as the expression of death ligands such as Fas ligand (FasL) and tumour necrosis factor-related apoptosis-inducing ligand (TRAIL) [69–71]. The gene discussed is FASLG; the disease is neoplasm.