Figure 3. Troglitazone inhibits 12-O-tetradecanoylphorbol-13-acetate (TPA)-induced activation of extracellular signal-regulated kinases (ERK), c-Jun N-terminal kinases (JNK), and protein kinase B (AKT) in MCF-7 cells. (A) MCF-7 cells were pretreated with inhibitors of ERK (PD98059), JNK (SP600125) and then TPA was added for 24 hours. Matrix metalloproteinase-9 (MMP-9) secretion was analyzed by gelatin zymography and protein was detected by western blot, respectively. (B) MCF-7 cells were pretreated with inhibitor of phosphoinositide 3-kinase (PI3K) (LY294002 and wortmannin) and then TPA was added for 24 hours. MMP-9 secretion was analyzed by gelatin zymography and protein was detected by western blot, respectively. (C) MCF-7 cells were pretreated with troglitazone and TPA was added for 24 hours. Phosphorylation of ERK, JNK, and AKT was analyzed by western blot. Total ERK, JNK, and AKT were the internal controls. Values are mean±standard error of the mean (SEM) of three independent experiments. (D) MCF-7 cells were pretreated with inhibitors of nuclear factor κB (Bay 11-7092) and activator protein-1 (curcumin) and then TPA was added for 24 hours. MMP-9 secretion was analyzed by gelatin zymography and protein was detected by western blot, respectively. Values are mean±SEM of three independent experiments.