Although it has been demonstrated that sildenafil administered for 3 weeks reduces oxidative stress in smoke induced erectile dysfunction in C57BL6 mice [59] and has been considered a novel therapeutic strategy to repair the endothelial dysfunction in apoE-/- mice [20], we cannot predict whether such beneficial effects on genotoxicity and oxidative stress are long-lasting in atherosclerosis. This evidence concerns the gene APOE and atherosclerosis.