Activation of PI3K-AKT and MEK-ERK1/2 signaling pathways contributes to cell survival in response to H
. PC12-GFP or PC12-SH2B1β cells were pre-treated with PI3K inhibitor (LY294002), MEK inhibitor (U0126) or mock-treated 1 h before the addition of H2O2 for 24 h. Cell viability was measured by MTT assays. Values are expressed as % of the respective controls (samples without H2O2 treatment) for each experiment, with the values obtained from respective control cells taken as 100%. Values are expressed as mean ± S.E. from five independent experiments. The asterisks represent significant differences compared between the indicated conditions (*, p < 0.05).