IκBζ associates with the IFN-γ promoter and activates luciferase expression in human NK cells. The binding of IκBζ to the IFN-γ promoter was studied by ChIP in human NK cells. IκBζ's function in promoting IFNG gene expression was studied in a luciferase reporter assay in HEK 293 cells stably transfected with TLR4/IL-1R/MD-2. (A) Top: Diagrammatic representation of 4 NF-κB binding sites (κB, C3-1P, C3-3P, and C3 1st intron as reported³⁷ ) present on the IFN-γ promoter. Bottom: The effect of IL-12/IL-18 stimulation on the relative enrichment of IκBζ association with the 4 NF-κB sites as determined by ChIP. (B) Top: Diagrammatic representation of the IFN-γ luciferase reporter construct used in the luciferase reporter assay. Bottom: The ability of IκBζ-L to induce expression of the IFN-γ luciferase reporter. Values are mean ± SEM for 3 independent experiments. **P < .05 vs controls. RLU indicates relative luciferase units.