PTEN and diabetic kidney disease: Another study in Drosophila where eye size was reduced due to RNAi-mediated knockdown of DJ-1, expression of Akt reversed this phenotype, suggesting that DJ-1 acts upstream of Akt kinase We and others have established a role for PTEN in renal cell hypertrophy and matrix expansion in rodent models of diabetic nephropathy [39, 49, 53, 104].