miR-451a interacts with the 3′-untranslated region (UTR) of the ATF2 mRNA and regulates ATF2 expression. A: the binding sites of miR-451a on ATF2 were predicted by DIANA. The region in the box shows the potential binding sequences (position 1880–1879). B: miR-451a mimic was cotransfected with the blank vector or ATF2–3′-UTR-vector into 293T cells. Luciferase activity was normalized by the ratio of Firefly/Renilla (mean ± SE, n = 3, *P < 0.05). C: ARPE-19 cells were transfected with miR-451a mimic and inhibitor or the corresponsive control. ATF2 mRNA levels at 48 h after transfection were measured by qRT-PCR. The ATF2 mRNA level was normalized to GAPDH (mean ± SE, n = 3, *P < 0.05). D: ARPE-19 cells were transfected with miR-451a mimic and inhibitor or their respective control, blank transfection (Mock), the nontreated control (Nontreated). ATF2 protein expression at 48 h after transfection was detected by Western blot analysis. E: the expression level was normalized to GAPDH levels (mean ± SE, n = 3, *P < 0.05, ****P < 0.0001).