Effect of NSC697923 related compounds on NF-κB activation induced by PMA. (A) Structures of the tested NSC697923 analogs. (B) 293T–NF-luc cells were pretreated with the indicated compounds (2μM) or DMSO (0.2%) for 1 hour. The cells were then stimulated with PMA for 20 hours or left untreated as indicated. Shown are the relative luciferase activities, which were normalized to GFP reading (mean ± SD; n = 4). The luciferase activity of the unstimulated samples was set at 1. (C) Structures of the tested nitrofuran-containing compounds. (D) 293T–NF-luc cells were pretreated with DMSO (0.02%) or various nitrofuran-containing compounds at the indicated concentrations for 1 hour and then stimulated with PMA for 6 hours. The means of the luciferase activities relative to the DMSO pretreated (control) samples from the triplicates are shown.