PRF1 and neoplasm: NK cells exhibit two different roles, in which CD56dimCD16high NK cells play a cytotoxic role, and release perforin and granzyme B after binding to target cells to mediate apoptosis, while CD56highCD16dim NK cells release IFN-γ, tumor necrosis factor, granulocyte-macrophage colony-stimulating factor, and other cytokines to induce other immune cells to attack the target tumor cells.