Inhibition of PI3K activity increases LPS-induced p38 MAPK activity. Wortmannin (1 μM and 10 μM) was administered to mesencephalic neuronal-microglia mixed cultures before LPS (1 μg/ml) was added and, after 30 mins, p38 MAPK was immunobloted. As shown in 4A, wortmannin enhances the phosphorylation of p38 MAPK under LPS stimulation in a dose-dependent manner (Fig 4A and 4B. p < 0.05), however, wortmannin did not increase p38 phosphorylation without LPS stimulation (Fig 4D). In contrast, inhibition of PI3K activity by wortmannin did not change JNK expression (Fig 4C). Data presented are representative of three independent experiments (n = 3). (*p < 0.05 vs. wortmannin 1 μM + LPS).