One of pathologic characteristics in atherosclerosis is the accumulation of increased lipid in cells.Macrophages uptake cholesterol by membrane receptor CD36 and SR-A_Ⅰ,and the cellular cholesterol efflux is mediated by SR-BⅠand ABC family.At the same time,various of proteins balance cholesterol via esterification and deesterification to prevent accumulation of cholesterol which may contribute to the formation of foam cell.