In this context, the exact source of these cells is unclear and controversial and only in few nephropathies such as diabetic nephropathy, the development of renal fibrosis is more clearly associated with intrarenal TGF-β1 induced transition of secondary epithelial cells towards myofibroblastic cells: the so-called Type II EMT [13–15]. The gene discussed is TGFB1; the disease is renal fibrosis.