FIGURE 5.

CSE alters HDM2/p53/p21 and ASK1/p38 signaling pathways and leads to cell death via decreased Akt activity. A, suppression of CSE-induced alteration in the HDM2/p53/p21 and ASK1/p38 pathways by expression of active Akt. Twenty four hours after transfection of the mock, active Akt (Myr Akt/Myc-His), or inactive Akt (DM Akt/Myc-His) plasmid, NHLFs were exposed to 8% CSE in serum-free DMEM for the indicated times. Each protein was quantified after normalization to GAPDH. Endo and Exo denote phosphorylated forms of endogenous and exogenously introduced Akt, respectively. B, suppression of CSE-induced cytotoxicity by expression of active Akt in NHLFs. After 24 h of transfection of the plasmids, NHLFs were seeded on 96-well plates. The next day, NHLFs were exposed to 8% CSE for the indicated times. Cell viability was evaluated by the MTT assay. Data represent the means ± S.D. Asterisks denote statistically significant difference (p < 0.05, Meck versus Myr Akt/Myc-His). Number of each group is six.