<prompt> All of the following take part in the pathogenesis of macular edema in diabetic retinopathy exceptRetinal pigment epithelium dysfunctionOxidative stressVEGFIncreased protein kinaseC  <response>: Etiopathogenis of diabetic retinopathy including macular edema Following factors are important in development of diabetic microangiopathy, which is responsible for the development of retinopathy :-Activation of protein kinase COxidative stressIncreased production of growth factors, amongst which Vascular endothelial growth factor A VEGF-A is the most important. Other factors are TGF - β, PDGF, EGF and IGF 