The effects of oAβ1-42 and 4-PSB-2 on the viability of human adult retinal pigment epithelial cell line (ARPE-19 cells). (A) The expression of oAβ1-42 in ARPE-19 cells: A11 (red), oAβ marker; DAPI (blue), nucleus; Bar, 100 µm. (B) A dose–response curve for RPE cells stimulated with 0.1 to 10 µM solutions of oAβ1-42 for 48 h demonstrates the mild effect of 10 µM oAβ1-42 on the viability of ARPE-19 cells (n = 5–6/group). (C) The morphology of ARPE-19 cells after 0.1 to 10 µM of oAβ1-42 treatment compared to control; Bar, 20 µm. The irregular shapes of cell bodies and nuclei of ARPE-19 cells (black arrows) and small vesicles in the cytoplasm (white arrows) were observed after oAβ1-42 treatment. (D) Chemical structure of 4-PSB-2. (E) ARPE-19 cells were treated with 0.1% dimethyl sulfoxide (DMSO) in control, 4-PSB-2 (1, 25, 50, 100, and 200 µM) for 24 h. MTT analysis showed that 4-PSB-2 was not toxic to ARPE-19 cells, and 25 µM of 4-PSB-2 significantly increased cell viability.(* indicates p ≤ 0.001 between the groups).