The level of apoE4(1–272) recovered from the mitochondrion-rich fraction is greater than that of apoE4(1–299). Neuro2a cells transfected with ApoE4(1–272) and ApoE4(1–299) plasmids were harvested and homogenized with a homogenizing buffer (10 mM Tris-HCl, pH 7.4, 1 mM EDTA, 0.25 M sucrose), and the resulting homogenate was centrifuged at 1,000 g for 10 min at 4°C. The resulting supernatant was further centrifuged at 8,000 g for 20 min at 4°C. The resulting precipitate (ppt) was used as the mitochondrion-rich fraction. Equal amounts of proteins from the ppt and supernatant (sup) fractions were analyzed by western blot analysis using the anti-apoE antibody, AB946, and the anti-VDAC antibody. VDAC was used as the mitochondrion marker.