CART transfection outperforms electroporation and causes minimal reconfiguration of NK cell phenotype. NK cells (500 000 cells per well) were transfected with GFP-encoding mRNA via L2000 (31 ng of mRNA per well), electroporation (31 ng per well [Elec] or 10 000 ng of mRNA per well [Elec high]), or CART O₅:N₆:A₉ (31 ng of mRNA per well). (A) Flow cytometric analysis of NK cell viability (top) and transfection efficacy (bottom) 18 hours posttransfection with GFP-encoding mRNA. (B) Uniform manifold approximation and projection (UMAP) dimensionality reduction of CyTOF data faceted by treatment condition. (C) Heatmap of mean marker expression, with samples and markers hierarchically clustered. *P < .05, ***P < .001, ****P < .0001 by paired Student t test; all other comparisons were not statistically significant at P = .05 level.