Decreased DNMT1 expression occurs in replicative senescent aortic SMCs and correlates with rates of hypomethylation of COL15A1 (over-expressed in the atherosclerotic lesion and localized to the atherosclerotic cap), this linking epigenetic regulation of DNMT1 with SMC phenotypes and prevalence rates of atherosclerosis (16). The gene discussed is DNMT1; the disease is atherosclerosis.