Rap1b expression decreased in tubules from human diabetic nephropathy and overexpression of constitutively active Rap1b improved renal tubular mitochondrial dysfunction, oxidative stress, and apoptosis in rats with streptozotocin-induced diabetes, in association with increased C/EBP-β and PGC-1α expression [188]. The gene discussed is PPARGC1A; the disease is diabetic kidney disease.