Previous studies of the corpora cavernosa in streptozotocin (STZ)-diabetic rats have shown significant decreases in the smooth muscle and endothelial cell densities 6 months after induction of diabetes (9), and decreased levels of endothelial nitric oxide synthase (eNOS) and nNOS isoforms 12 weeks after diabetes induction (10). The gene discussed is NOS1; the disease is diabetes mellitus.