Figure 4. Expression of visual cycle genes increases in the differentiated RPE cells. ARPE-19 cells grown for either 4 days or 4 months were used for total RNA and protein extractions and were used for real-time quantitative PCR and western blotting, respectively, as described in the Methods section. A: Real-time PCR analysis of RPE-specific mRNA expression. The values are mean ± standard deviation (SD), n = 4. *p<0.001 compared with control. B: Western blot analysis of the expression of the RPE-specific proteins. α-Tubulin expression shows that the amount of protein used in the different samples is similar.