NF-κB induced by TNF-α inhibits T₃-dependent induction of 5′-DI. T₃-dependent induction of 5′-DI Luc activity was inhibited by NF-κB induced with TNF-α. T₃-dependent induction of 5′-DI Luc was also inhibited by transfection of the plasmid expressing p65. This inhibition was reversed by transfection of the plasmid expressing p65 DN. (a) The values of Luc/β-gal activity with or without T₃. ^AP < 0.001, ^BP < 0.0001 vs. TR, T₃ (+); ^CP < 0.0001, TR, T₃ (+), TNF-α vs. TR, T₃ (+), TNF-α, p65 DN. (b) Fold induction by T₃. ^DP < 0.001, ^EP < 0.0001 vs. TR; ^FP < 0.0001, TR + TNF-α vs. TR + TNF-α + p65 DN.