APOE and atherosclerosis: In previous studies, ABCA1 expression in the endothelial-specific promoter in C57BL/6 mice and ABCA1-overexpressing C57BL/6 mice showed a plasma HDL increase and a reduction of atherosclerosis [57], while ABCA1-overexpressing mice in an Apoe-null background did not show any changes in HDL level [58].