Functional activation of Rac1 requires specific guanine exchange factors, including Tiam1 and Sos1, and in diabetes, Tiam1-mediated activation of Rac1 is implicated in retinal Nox2-ROS production.2,5 Hyperglycemic milieu also increases Rac1 transcription, and our recent work has shown that hyperglycemia promotes this transcriptional activation by increasing the binding of nuclear transcriptional factor-κB (NF-κB, p65 subunit) at the Rac1 promoter.6 However, the putative mechanism underlying increased transcription factor binding remains to be explored. This evidence concerns the gene CYBB and diabetes mellitus.