CYBB and diabetic retinopathy: Rac1-Nox2-ROS signaling is one of the early events in the pathogenesis of diabetic retinopathy; in retinal endothelial cells it can be seen within 6 hours of high glucose insult.2 To investigate if DNA-methylation-hydroxymethylation is playing any role in the early activation of Rac1, DNA methylation status of Rac1 promoter was analyzed in HRECs exposed to high glucose for 6 to 48 hours.