Besides renal dysfunction, db/db mice displayed glomerular hypertrophy (Fig. 1c,d), mesangial expansion (Fig. 1e,f), elevated collagen type IV (Fig. 1g) and TGF-β (Fig. 1h,i) expression in the glomeruli, all markers of renal pathology associated with diabetic nephropathy. Here, TGFB1 is linked to diabetic kidney disease.