ApoE-derived peptide affects APP processing and Aβ production in vivo. A. sAPPα was measured from wild-type mice injected with vehicle control (C) for 4 h (n = 6), apoE dimer (D) for 4 h (n = 6) or apoE dimer (D) for 24 h (n = 6). Wild-type mice showed an increase in sAPPα after 24 h and a slight increase in sAPPα after 4 h compared with control treated mice. B. Quantification of experiments demonstrated that injection with the apoE dimer significantly increased sAPPα by 77% after a single injection (*p < 0.01). C. Quantification of experiments demonstrated that injection with the apoE dimer did not alter sAPPβ. D. Aβ1-40 was measured from wild-type mice injected with PBS for control (n = 9), or apoE dimer at 1 mM (n = 9) or 10 mM (n = 8) for 24 h. ApoE dimer-treated mice showed a 40% decrease in Aβ1-40 at 1 mM after 24 h and a slight 26% decrease in Aβ1-40 at 10 mM after 24 h compared with control-treated mice. E. Aβ1-42 was measured from the same animals and was not significantly different in either 1 mM or 10 mM injected animals compared to control. F. Rodent Aβ1-42 was measured from samples containing the apoE dimer peptide alone, synthetic rodent Aβ42 alone, synthetic rodent Aβ42 with PBS, or synthetic rodent Aβ42 with apoE dimer peptide. Aβ1-42 values were normalized to background with apoE dimer peptide alone, and were not found to be significantly different in the presence of PBS or apoE dimer peptide.