Suzaki et al. (2004) identified a potential role for Erk5 in the pathogenesis of the diabetic kidney describing increased activation of Erk5 in the glomeruli of diabetic rats and using in vitro techniques to demonstrate its activation in mesangial cells by high glucose. The significant role that Erk5 might possess in diabetic nephropathy was furthered in later reports by our group and others of TGFβ1-mediated activation of Erk5 in both renal tubule epithelial cells and mesangial cells (Browne et al., 2008; Dorado et al., 2008). This evidence concerns the gene TGFB1 and diabetic kidney disease.