Figure 4. TNF-α upregulates VEGF expression in RPE cells via ROS-dependent signaling. A: Western blot of vascular endothelial growth factor (VEGF) in RPE cells treated with tumor necrosis factor alpha (TNF-α; 20 ng/ml) for 3, 6, or 12 h. B: Quantitative PCR of VEGF mRNA in RPE cells pretreated with apocynin (100 µM) or control for 30 min before incubation with TNF-α (20 ng/ml) for an additional 12 h (***p<0.001 versus PBS of control; ^†p<0.05 versus TNF-α of control).