S1PR1 and atherosclerosis: On the other hand, S1PR1 may have a positive effect on the development of atherosclerosis by activating pro-inflammatory endothelial factors such as: intercellular adhesion molecule (ICAM-1) and vascular cell adhesion molecule 1 (VCAM-1), as well as by facilitating the formation of neointima formation by increasing the level of interleukin 6 (IL-6), which stimulates the proliferation and migration of vascular smooth muscle cells (VSMCs) (61, 62).