To achieve a maximal reduction in plasma lipids, the MTPi treatment was combined with a diet switch to a normal chow, since in a previous study, feeding hyperlipidemic apoE-/- mice with a western-type diet along with MTP inhibitor treatment maintained high plasma levels of cholesterol (500 mg/dl) and failed to result in regression of atherosclerosis [13]. This evidence concerns the gene APOE and atherosclerosis.