FIG. 9.
The stimulatory effects of PP2A inhibition on glucose uptake and GLUT4 translocation are not inhibited by wortmannin. (A) 3T3-L1 adipocytes infected with either control virus or small-t-antigen-encoding adenovirus (ST) were starved, pretreated with 100 nM wortmannin for 30 min, and then stimulated with insulin (100 ng/ml) for 30 min. Glucose (2-DOG) uptake was measured as described in Materials and Methods. Data are presented as the increase (n-fold) in glucose uptake compared to unstimulated control cells and represent the mean ± SE of results from three independent experiments. (B) 3T3-L1 adipocytes on coverslips were microinjected with anti-PP2A antibody (Ab) or with sheep IgG as a control. Cells were starved, pretreated with 100 nM wortmannin for 30 min, and then stimulated with insulin for 20 min. Fixed cells were stained with rabbit anti-GLUT4 antibody, as described in Materials and Methods. The percentage of cells positive for GLUT4 translocation was calculated as described in Materials and Methods. The data shown are the mean ± SE of results from four independent experiments.