Fig. 7. Agents that inhibit GSK3 activity also block ER stress-induced lipid accumulation and apoptosis. (A) Determination of caspase 3 activity in HepG2 cells pretreated for 1 hour in the presence or absence of 20 mM LiCl and then exposed to 0 or 20 µg/ml tunicamycin for 6 hours as indicated. Caspase 3 activity was determined in cell lysates and normalized to total protein concentrations. Data are presented as the mean±s.d. of three independent experiments. *P<0.01 when compared to the corresponding control. (B) Filipin staining of HepG2 cells pretreated for 1 hour in the presence of 0.5 mM valproate, 20 mM LiCl or 20 µM GSK inhibitor II (GSKin) and then challenged with 0 or 5 mM glucosamine as indicated. After 24 hours, cells were washed, fixed in paraformaldehyde and stained with filipin. Intracellular filipin-cholesterol complexes were visualized by fluorescence microscopy. (C) Median fluorescence of filipin-stained cells treated as described in B. *P<0.01 when compared to the corresponding control. **P<0.01 compared to relative fluorescence in the absence of GSK3 inhibition.