Additionally, the protein expressions of heme oxygenase‐1 (HO‐1), glutamate‐cysteine ligase catalytic subunit (GCLC), and NAD(P)H dehydrogenase (quinone 1) (NQO1) were all significantly reduced in mice with diabetic retinopathy, and all were significantly restored by the supplement of GSP (Figure 4d,f–h). This evidence concerns the gene NQO1 and diabetic retinopathy.