Human miR-27a* down-regulates NK-cell cytotoxicity by silencing Prf1 and GzmB. (A-D) Overexpression and knockdown of miR-27a* induce decrease and increase of NK-cell cytotoxicity, respectively. mNK cells transfected with Ctrl_miR, miR-27a, or miR-27a inhibitor were analyzed for IB (A top), standard Cr release assay (A bottom), ELISA for de novo synthesis of TNF-α (B red), and IFN-γ (B blue), conjugation assay using 2-color FACS cytometry (C), and FACS analysis from the CD56⁺-gated lymphocyte population (D). Data are representative of 3 independent experiments. The quantitative data are expressed as the mean value of independent measurements from 3 separate experiments (mean ± SEM; Student t test, **P < .01 and ***P < .001 vs Ctrl_miR). (E) Level of Prf1 and GzmB protein is an essential regulator of NK-cell killing capacity. (Top) IB analysis. (Middle) Real-time qPCR. (Bottom) Standard Cr release assay. Data are representative of 4 independent experiments (mean ± SEM of triplicates; Student t test, ***P < .001 vs Ctrl_siRNA.