Figure 4. SKF83959 treatment preserved active levels of ERK in H₂O₂-treated RGC-5 cells. A: Pretreatment with 30 μM SKF83959 prevented the H₂O₂-induced reduction of p-ERK levels. Treatment with the specific inhibitor of MEK/ERK, 20 μM U0126, abolished the SKF83959-induced increase of p-ERK. SKF: SKF83959. Each experiment was repeated at least three times, and a representative blot is shown. B: The reduction of p-ERK was quantitatively measured, and statistical significance was analyzed. Data were obtained from at least three independent experiments and expressed as the mean±SEM ***p<0.001, compared to control. C: U0126 attenuated SKF83959-mediated neuroprotection. RGC-5 cells were pretreated with 20 μM U0126 30 min before 30 μM SKF83959 was added in the presence of 500 μM H₂O₂ for 5 h. Cell viability was determined with MTT assay. Data were obtained from at least three independent experiments and expressed as the mean±SEM ***p<0.001, compared to SKF83959-pretreated cells.