S1PR1 and atherosclerosis: Moreover, endothelial progenitor cells (EPCs) are able to prevent the development of atherosclerosis by repairing endothelial damage and restore monolayer integrity and function, S1P promotes EPCs proliferation and inhibits their apoptosis through S1PR1 and S1PR3 to activate the PI3K/Akt signalling pathway (Figure 4B).49