ApoE isoforms reduce phosphorylation of GSK 3β and P35. Panel A: Cells were treated with control buffer ("C"), apoE2 ("E2"), or apoE4 ("E4") at 2 uM for 2 hours. Cell lysates (20 ug/lane) were electrophoresed and immunoblotted for P-GSK 3β, P35, and β-actin. ApoE2 and E4 treatment resulted in decreased levels of P-GSK3β and P35. Panel B: ApoE2 caused the greatest decreases in GSK 3β phosphorylation, and apoE4 the least, with significant differences observed between each of the apoE isoforms. Both E2 and E4 caused significant decreases in P35, 96% and 79%, respectively. Panel C: Cells were treated with control buffer, E2, or E4 at 100 nM for 12 hours. Cell proteins were probed for P-GSK 3β, P35 and β-actin. Panel D: Neither apoE isoform at 100 nM had a significant effect on P-GSK3β and P35 levels.