Figure 4. Inhibitory effect of bortezomib on RPE cell contraction. A: Contraction assay of the RPE–collagen gel complex in the presence or absence of 20 nM bortezomib. Bortezomib efficiently inhibited gel contraction. B: Statistical analysis of the gel area revealed that bortezomib decreased gel contraction after 24 h. ***p<0.001 with an independent t test, n=3, standard error. C: Microscopic observation revealed that cell spreading and cell-to-cell adhesion were impeded in the presence of bortezomib. D: Staining of filamentous actin revealed that the formation of stress fibers was inhibited in the presence of 20 nM bortezomib..