APOE and atherosclerosis: The present study investigated the effects of pulmonary exposure to single-walled carbon nanotubes (SWCNTs) and double-walled carbon nanotubes (DWCNTs) on atherosclerogenesis using normal human aortic endothelial cells (HAECs) and apolipoprotein E-deficient (ApoE−/−) mice, a model of human atherosclerosis.