The Ldlr−/− mouse is a widely used experimental model to study atherosclerosis, but we and others have previously shown that severe hypercholesterolemia induced by a Western diet (WD) is needed to promote atherosclerosis in young (3 months) Ldlr−/− mice (Fig. 1A-D) [15]. This evidence concerns the gene LDLR and familial hypercholesterolemia.