SOD1 and diabetic retinopathy: Knocking out circ-UBAP2 in the miR-589-5p/EGR1 axis alleviates high glucose-induced oxidative stress and vascular dysfunction in human retinal microvascular endothelial cells (HRMECs) by increasing superoxide dismutase (SOD) and glutathione peroxidase activities and nuclear factor erythroid 2-related factor 2 (Nrf2), HO-1, and SOD-1 expression, which provides a promising therapeutic target for diabetic retinopathy [88].