RAC1 and diabetic retinopathy: Rac1 also activates stress kinases such as p38MAPK, and in addition to their role in mitochondrial damage, stress kinases alter several facets of the retinal physiology that contribute to the pathological development of diabetic retinopathy including alteration in the tight junctions, breakdown of blood retinal barrier and activation of matrix metalloproteinases (MMPs) [44,45,46,47].