Apolipoprotein E (APOE) is a glycoprotein that is involved in the regulation of lipid metabolism. In the central nervous system, it is found in astrocytes, microglia, blood vessel wall cells, and choroid plexus cells. APOE is polymorphic and contains three allelic mutants: APOE*ε2, APOE*ε3, and APOE*ε4. Learn more: Apolipoprotein E Antibodies