Figure 4. Effects of nuclear factor factor-kappaB and mitogen-activated protein kinase inhibitors on the hydrogen peroxide-induced production
of interleukin-6 by retinal pigment epithelium cells. Retinal pigment epithelium (RPE) cells (ARPE-19) were plated into 24-well
plates. After 24 h incubation, various mitogen-activated protein kinase (MAPK) and nuclear factor-kappaB (NF-κB) inhibitors
were added to the medium separately, including BAY11–7082 (NF-κB inhibitor), UO1026 (extracellular signal-regulated kinases
inhibitor), SP600125 (c-Jun N-terminal kinase inhibitor) and SB203580 (p38 MAPK inhibitor, all from Calbiochem) at a final
concentration of 10 µM with the exception of BAY11–7082 (5 µM). After 30 min, 100 µM hydrogen peroxide (H2O2) was added to the medium. Cells cultured without H2O2 were used as negative controls. Cells cultured with H2O2 but without inhibitors were used as positive controls. After 24 h incubation, the culture medium was collected and the IL-6
levels were measured with the human IL-6 Quantikine ELISA kit and expressed as pg/ml (mean±standard deviation in triplicate
tests). *0.01< p<0.05, **p<0.01, compared with the positive controls (cells cultured with H2O2 but without inhibitors).