CCN2 and diabetic kidney disease: Although we are not aware of any clinical, experimental, or in vitro studies addressing CTGF expression specifically in medullary tubules in diabetic kidney disease, increased tubular CTGF protein expression has been reported before, both in human and in experimental diabetes, and was postulated to contribute to tubulointerstitial fibrosis via paracrine effects at the basolateral membrane [4, 33–35].