Effects of overexpression of apoE4(1–272) and apoE4(1–299) on ATP synthase activity and mitochondrial membrane potential. The ATP synthase activity in Neuro2a cells transfected with the ApoE4(1–272) and ApoE4(1–299) plasmids were determined (A) as described in the Methods. The data are the mean ± SEM of three experiments. (B) Flow cytometry plots were used to determine the ratio of cells having normal and low mitochondrial membrane potentials, which were demonstrated by staining with the JC-1 dye. The distribution of the cells sorted by FACS was analyzed, and the ratios of the number of cells showing normal membrane potential (C) and low membrane potential (D) to total cell number were calculated.