Fig. 6. Effects of ER stress-inducing agents and valproate on GSK3/ß activity. (A) GSK3 and -ß activity immunoprecipitated from cells exposed to 10 µg/ml tunicamycin or 10 µM A23187 for 2 hours. Quantitative values are expressed as a percentage of GSK3 or -ß activity in untreated cells. Data are expressed as the mean±s.d. (n=3). (B) Recombinant GSK3 and -ß activity in the presence of 0-5 mM valproate or 0-50 mM lithium. Quantitative values are expressed as a percentage of recombinant GSK3 or -ß activity in the absence of inhibitor. Data are expressed as the mean±s.d. (n=3). *P<0.05 relative to activity in the corresponding control. (C) GSK and -ß activity immunoprecipitated from HepG2 cells. Valproate (0.5 mM) was added in vivo to the cells 2 hours prior to harvesting and immunoprecipitation or to the immunopurified GSK3 during the kinase assay as indicated. Quantitative values are expressed as a percentage of GSK3 or ß activity in untreated cells. Data are expressed as the mean±s.d. (n=3). *P<0.05 relative to levels in the corresponding control.