ABCG1 is an ATP-binding cassette transporter that catalyzes the efflux of phospholipids, cholesterol, and oxysterols like 7β-hydroxycholesterol from cells in an ATP-dependent manner 1. This lipid efflux is albumin-dependent and operates through a well-defined cholesterol-binding cavity where sphingomyelins facilitate cholesterol recruitment and hydrophobic residues mediate release to HDL acceptors 1. ABCG1 functions as a key component of reverse cholesterol transport, forwarding cellular cholesterol to nascent HDL particles and preventing cytotoxic oxysterol accumulation 2. Beyond macrophages, ABCG1 regulates lipid homeostasis broadly, including in adipose tissue macrophages where it controls saturated fatty acid distribution and inflammatory responses 3. Clinically, ABCG1 dysfunction contributes to atherosclerosis pathogenesis: oxidized LDL downregulates ABCG1 expression via epigenetic mechanisms, promoting foam cell formation and sustained proinflammatory responses 4. Conversely, enhanced ABCG1 activity suppresses macrophage inflammatory cytokine production and reduces cholesterol accumulation, strategies considered protective against atherosclerosis progression 56. ABCG1 also prevents amyloid-β accumulation, suggesting potential relevance to Alzheimer's disease 5. Multiple regulatory mechanisms—transcriptional, post-transcriptional, and post-translational—control ABCG1, making it an attractive therapeutic target for cardiovascular disease prevention.