Figure 1. Effects of bortezomib on proliferation and cell cycle of APRE-19. A: Microscopic observations of a human RPE cell line (ARPE-19) in the presence or absence of 20 nM bortezomib. B: After various concentrations of bortezomib (0, 0.2, 2, and 20 nM) were applied, we evaluated cell viability with the water-soluble tetrazolium salt-8 (WST-8) assay. At a concentration of 20 nM bortezomib, cell viability was statistically significantly reduced (p<0.001). Data represent the mean ± standard deviation (SD) of three replicates. ***p<0.001 with one-way ANOVA, followed by Tukey’s honest significant difference (HSD) post-hoc test. C: Flow-cytometric analysis revealed that bortezomib induced arrest of the G2/M phase at 24 and 48 h. D: After treatment with bortezomib, the proportion of RPE cells in the G2/M phase was statistically significantly higher than that in the control samples (p<0.001). ***p<0.001 with an independent t test, n=3, standard error.