Expression of PD-L1 is induced by STAT3 in NKTL. (A) Protein expression of pSTAT3 (Y705), total STAT3, and PD-L1 examined by western blot in NKTL cell lines at basal state. (B) Expression of PD-L1 mRNA examined by RT-qPCR in NKTL cell lines at basal state, and results were normalized against housekeeping gene CHMP2A. (C) Expression of membranous PD-L1 examined by flow cytometry in NKTL cell lines at basal state. (D) NK-S1 cells were transduced with empty vector, STAT3^WT, p.E616K, and p.E616G expression vectors. The pSTAT3 and total STAT3 protein levels in these cells were detected with western blot. (E) PD-L1 mRNA in these cells was detected by RT-qPCR. Results were represented as fold change relative to empty vector and normalized against housekeeping gene CHMP2A. (F) Membranous PD-L1 expression in these cells was detected by flow cytometry. All results are expressed as mean ± SD of 3 independent experiments. *P < .05 compared with empty vector; #P < .05 compared with STAT3^WT.