FIGURE 6.

Knockdown of Cbl and CAP blocks metformin-induced GLUT4 translocation. A, 3T3-L1 preadipocytes were transiently transfected with CAP, Cbl, or nontarget siRNA for 48 h. Cell lysates (25 μg) were analyzed by Western blotting (IB) with the anti-CAP or anti-Cbl antibody. Blotting with the anti-β-actin antibody was used as a protein-loading control. B, L6-GLUT4myc-tagged cells were transfected with CAP or Cbl siRNA for 48 h. Cells were then treated with 10 mm metformin for 30 min. Cell surface GLUT4myc levels on intact cells were determined as described under “Experimental Procedures.” Each value is expressed as the mean ± S.E. (error bars) of three independent determinants. *, p < 0.05 versus metformin-treated condition.