IκBζ coimmunoprecipitates with NF-κB specifically in the nucleus of human NK cells. (A) To assess the ability of IκBζ to bind to NF-κB, human NK cells were stimulated with recombinant IL-12 and IL-18 (10 ng/mL each) for 6 hours. The cell lysates were immunoprecipitated with the indicated antibodies overnight at 4°C. The immunoprecipitated lysates were immunoblotted with respective antibodies as indicated in the figure. (A) IκBζ binding to the p65 NF-κB subunit. (B) IκBζ binding to the p50 NF-κB subunit. (C) Binding of IκBζ to NF-κB specifically in the nucleus. Arrowhead represents p50 NF-κB subunit; and arrow, immunoglobulin heavy chain. *(Black) IκBζ-L band. *(White) Nonspecific smudge mark on the Western blot. Results are representative of 3 independent experiments. Lamin B1, nuclear marker. LDH indicates lactate dehydrogenase (cytosolic marker).