Panel A: Primary neurons were treated with control buffer ("C") or 100 nM apoE2 (left panel) and E4 (right panel) for 12 hours. Cells were lysed in RIPA buffer (n = 4) and cell proteins (20 ug/lane) were separated by SDS-PAGE. Relative levels of tau epitopes were determined by immunoblotting with 5E2, Tau-1, and AT8 antibodies. Neither apoE2 (100nM) nor E4 (100nM) significantly changed the levels of tau phosphorylation compared with control. No significant changes in β-actin were observed. Panel B: Quantification of these blots revealed no significant changes in 5E2, Tau-1, and AT8. N = 4 for all blots listed above and their quantification averages are what is depicted in the figure. Panel C: Primary neurons were treated with control buffer ("C") or 100 nM EP for two hours, and cellular proteins analyzed by immunoblot for phospho-GSK-3β, CDK5, AT8, AT270 and β-actin as above.