Figure 5. Pirfenidone had no effect on transforming growth factor (TGF)-β1-induced phosphorylation of mitogen-activated protein kinase. Human retinal pigment epithelial cells (ARPE-19) cells were incubated in the absence or presence of pirfenidone (500 mg/l) for 1 h, and then treated with transforming growth factor-β1 (TGF)-β1 (10 μg/l) for varying time periods. Total cell lysates (50 μg total protein) were subjected to immunoblot analysis for p38 mitogen-activated protein kinase, c-Jun N-terminal kinase, extracellular signal-related kinase, and β-actin.