APC-mediated activation of CD8+ cytotoxic T lymphocytes (CTLs) exit lymphoid organs, infiltrate tumors, and exert anti-tumor effects by inducing apoptosis in tumor cells through granule exocytosis (involving perforin and granzymes) and engagement of death receptors (such as Fas ligand and tumor necrosis factor-related apoptosis-inducing ligand) (27, 28). Here, PRF1 is linked to neoplasm.