ABCG2 and atherosclerosis: For example, members of the ABC transporter superfamily, ABCA1 and ABCG1, facilitate cholesterol efflux from foam cells to the extracellular cholesterol receptors Apolipoprotein AI (ApoA-I) and high density lipoprotein (HDL), respectively, restricting foam cell development and slowing the progression of atherosclerosis [30,31].