Compound NSC697923 inhibits NF-κB activation induced by PMA, but not by TNFα. (A) The chemical structure of NSC697923. (B) 293T–NF-luc cells were pretreated with the indicated concentrations of NSC697923 or DMSO (final concentration 0.2%; control) for 1 hour. The cells were then stimulated with PMA (100 ng/mL) or TNFα (10 ng/mL) for 6 hours, and the green fluorescence (from GFP for normalization) and luciferase activity in the cell lysate were measured. Data are expressed as the percentage activity of the control (mean ± SD; n = 3). (C) 293T–NF-Luc cells were pretreated with 1μM NSC697923 for 1 hour before being stimulated with PMA or TNFα as indicated. The cells were harvested at the indicated times after stimulation, and phosphorylation of IKK and IκBα were analyzed by Western blotting. Analysis of actin was used as the loading control.