Free cholesterol is either effluxed from cells to HDL (reverse cholesterol transport) via the lipid transporters ABCA1 and ABCG1, key players in atherosclerosis, or trafficked to the ER, where it is reconverted into cholesteryl esters and stored in lipid droplets [231] (Fig. 2C). The gene discussed is ABCG1; the disease is atherosclerosis.