NF-κB is required for PD-L1 expression.

<p><b>A</b>. Indicated cells were transfected with control si (-) or siRNAs against p65 (+) for 48 hours and treated with 100ng/ml IFN-γ for an additional 48 hours before they were harvested for immunoblotting for the indicated proteins. V2 si RNA transfection was done independently with the accompanying control siRNA. One representative out of three independent blots is shown. <b>B</b>. <b>C</b>.KMJR138 cells were transfected with either control (-) or two independent siRNA targeting p105/p50 (+) for 48 hours and treated with 100ng/ml IFN-γ for an additional 48 hours before being harvested for immunoblotting for the indicated proteins. One representative out of three independent blots is shown. <b>C.</b> Cells were transfected with either IκBwt-GFP (control vector) or IκBmutant-GFP (super-repressor) using lipofectamine 2000 for 48 hours after which 100ng/ml IFN-γ was added. PD-L1 expression was detected by flow cytometry on GFP gated cells and is represented as MFI; the average of two independent experiments is indicated. *p-value = 0.01.