Stimulation of CD40 mRNA synthesis and protein production in hRPE cells. CD40 mRNA expression in hRPE cells, unstimulated or with IFN-γ (IFN) for 1.5, 3, 6, 24, 48, and 72 hours (A). FBS had no effect on stimulation. Western blot analysis of CD40 protein expression in hRPE cells at 24 hr of stimulation with IFN-γ (B). Fold changes in mRNA levels were calculated by comparison with unstimulated control after normalization against β-actin. An antibody against actin was used in the Western blot analysis as a loading control. The concentration of IFN-γ used was 500 U/ml. FBS, fetal bovine serum.