We acknowledge that our study has focused on ceramide-mediated transcriptional activation of Rac1, however, guanine exchange factors Tiam1 and Vav2 are also intimately associated with the functional activation of retinal Rac1 signaling in diabetic retinopathy, and inhibition of guanine exchange factors prevents activation of Rac1–Nox2–ROS signaling and inhibits mitochondrial damage and the development of retinopathy in diabetic mice40. This evidence concerns the gene TIAM1 and retinal disorder.