Effect of STAT3 silencing and inhibition on PD-L1 expression in STAT3 mutant NKTL cell lines. STAT3 mutant NKTL cell lines NKYS and SNK6 cells were nucleofected with nonspecific and STAT3-specific Gapmer for 72 hours. These cells were harvested for (A) western blot analysis of pSTAT3, total STAT3, and PD-L1; (B) RT-qPCR to detect PD-L1 mRNA; and (C) flow cytometry to detect membranous PD-L1 expression. NKYS and SNK6 were incubated with dimethyl sulfoxide vehicle or 1 µM Stattic for 24 hours. These cells were harvested for (D) western blot for pSTAT3, total STAT3, and PD-L1; (E) RT-qPCR to detect PD-L1 mRNA; and (F) flow cytometry to detect membranous PD-L1 expression. PD-L1 mRNA was represented as fold change relative to control and normalized against housekeeping gene CHMP2A. Membranous PD-L1 was represented as MFI fold change relative to control. All results are expressed as mean ± SD of 3 independent experiments. *P < .05 compared with control.