Figure 4. Jun N-terminal kinase (JNK) and P38 inhibitors block tumor necrosis factor (TNF)-induced Forkhead box O1 (FOXO1) activation and apoptosis. Primary bovine retinal pericytes were preincubated with or without the p38 inhibitor or JNK inhibitor for 2 h, followed by TNF-α (20 ng/ml) or carboxymethyllysine (CML)-collagen (200 μg/ml) stimulation. A: Activation of FOXO1 in response to TNF-α or CML-collagen stimulation (1 h) was measured by electrophoretic mobility shift assay (EMSA). Unlabeled FOXO1 in excess was used as a competitive inhibitor. B: Effect of JNK and P38 inhibitors on TNF-α-induced apoptosis (24 h) was determined by ELISA. C: Effect of JNK and P38 inhibitors on AGE-induced apoptosis (24 h) was determined by ELISA. Each value represents the mean of three replicates±standard error of the mean and is representative of three experiments. *, p<0.05 significantly differs from control (B) or control collagen (C); **, p<0.05, significantly differs from TNF-α- or CML-collagen-stimulated cells.