APOM and atherosclerosis: It was reported that S1P transported by HDL-associated ApoM may act on S1P1 and three receptors, inducing anti-atherogenic and vasculoprotective effects [26], while S1P carried by HDL-ApoM can also bind to S1PR2, leading to macrophage retention in the atherosclerotic plaques and the promotion of atherosclerosis [27].