ABCA1 and atherosclerosis: Studies in mice in which the Abca1 locus is either deleted or overexpressed generally have supported the hypothesis that ABCA1 significantly prevents atherosclerosis by maintaining circulating HDL-C levels and cellular cholesterol efflux.10–13 Tissue-specific knockouts of the Abca1 locus were generated and revealed that liver and macrophage ABCA1 both play roles in preventing atherosclerosis.14 ABCA1 modulates cell-surface cholesterol levels, inhibits its partitioning into lipid rafts, and decreases the responsiveness of inflammatory signals from innate immune receptors.