APOM and coronary artery disorder: However, because S1P in HDL is responsible for many pleiotropic functions of HDL, a low S1P level is a critical characteristic of HDL dysfunction in CAD.65 ApoM affects the biological functions of S1P, and ApoM-bound S1P exerts more potent effects on S1P1 in endothelial cells.30,60,66 Here, we showed that ApoM enhanced the inhibitory effect of S1P on HDRACA in endothelial cells.