MMP9 and diabetic retinopathy: Consistent with the results from in vitro and in vivo models, H3K27me3 levels were elevated by over 2.5-fold and Ezh2 binding was increased by approximately 4-fold at the MMP-9 promoter in microvessels from donors with diabetic retinopathy compared with their age-matched nondiabetic donors (Fig. 8a).