PRF1 and neoplasm: In addition to CTLs, natural killer (NK) cells are an important immune regulatory cell[94] that can destroy tumor cells by secreting perforin and granzyme B without a need for prior sensitization.[95] Recently, the strategy of antibody‐dependent cell‐mediated cytotoxicity (ADCC)[96] has attracted increased attention and even achieved successful clinical results, wherein the antibodies act as a bridge to link the NK cells with tumor cells.