Effect of PI3,4-P2 and PI4,5-P2 (5 μM) on Akt phosphorylation and neuronal survival. (A) Protein extracts (40 μg per lane) from neurons treated with PI3,4-P2 or PI4,5-P2 for 15 min 4 h after glia deprivation were immunoblotted for P-Akt. Densitometric analysis of the bands showed a statistically significant increase of 86 ± 3% in the presence of PI3,4-P2 (n = 3, P < 0.05). (B) In survival experiments, PI3,4-P2 ± gp120IIIB was added to the 7th day of culture in the absence of glia. Data are from two different experiments; ≈1,500 cells were analyzed for each treatment (**P < 0.01).