ABCA2 is a large ATP-binding cassette transporter primarily localized to endolysosomal membranes that plays a crucial role in lipid homeostasis 1. The protein functions as a probable lipid transporter that modulates cholesterol sequestration in late endosomes/lysosomes by regulating intracellular sphingolipid metabolism, thereby participating in cholesterol homeostasis 2. ABCA2 appears to alter the transbilayer distribution of ceramide, facilitating ceramide deacylation to sphingosine and leading to cholesterol sequestration in lysosomes 2. The transporter is most highly expressed in brain tissue and macrophages, where it shows sterol-dependent regulation and is coordinately expressed with other cholesterol-responsive genes 3. ABCA2 has been implicated in multiple disease processes, including drug resistance in cancer cells, where overexpression confers resistance to compounds like estramustine and mitoxantrone 4. Additionally, a single nucleotide polymorphism in ABCA2 has been linked to early-onset Alzheimer's disease, with the transporter influencing amyloid-beta peptide levels 4. The protein is also expressed in myelinating cells and may play a role in myelin formation, as suggested by its expression in oligodendrocytes and Schwann cells 5.