PRF1 and cancer: Currently, natural killer (NK) cell therapy, a new type of cancer immunotherapy, has a unique advantage of discriminating the malignant from healthy cells, thus achieving encouraging output in pre‐clinic and clinic state research.[1] According to statistics, totally, there are over two hundred of clinical trials investigating variety of NK cell immunotherapies to treat hematologic and solid malignancies in 2021.[2] NK cells exert the anti‐cancer activity mainly through: 1) secreting perforin and granzymes to kill cancer cell; or 2) directly induce cell apoptosis mediated by death receptor.