Figure 6. R9-SOCS3-KIR enhanced the antioxidant response in paraquat-treated ARPE-19 cells. ARPE-19 cells were grown overnight in 12-well plates. They were placed in a 1% FBS-containing medium and treated with R9-SOCS3-KIR (20 μM) for 1 h and then with paraquat (300 μM) for 4 h. The cells were washed, and RNA was extracted and used for cDNA synthesis. Quantitative RT-PCR was performed using the primers for the target genes indicated above, and β-actin served as the internal control. The units represent the expression level relative to β-actin. The Student’s t-test for unpaired data was used to calculate the statistical significance in each set of samples. **, p < 0.01, ***, p < 0.001. Abbreviations: HO-1, heme oxidase 1; SOD2, superoxide dismutase 2; Nrf2, NFE2-like BZIP transcription factor 2; NQO-1, NAD(P)H quinone dehydrogenase 1.