Fig. 3. A77 1726 sensitizes insulin receptor in L6 myotubes.

This experiment and the remaining ones (Fig. 4–7) were carried out under the condition of insulin resistance in which the cells were incubated in the presence of high concentrations of amino acids. Briefly, L6 myotubes were first starved of serum for 4 hr and then incubated either in an amino-acid free medium (EBSS) or EBSS medium containing 2x the amino acid concentrations (2xAA) found in MEM in the absence or presence of A77 1726 (200 μM) for 2 hr. After stimulation with insulin (20 nM) for 20 min, cells are harvested and analyzed for the phosphorylation of AKT^S473/T308 (A), S6K1^T389 (B), IRS-1^S1101 (C), S6^S235/236 (D), and reprobed with their specific antibodies for total proteins. Relative protein phosphorylation was analyzed by using an Image J software. The results are the mean ± SD from three experiments. A77, A77 1726; Rapa, rapamycin. *p<0.05; **p<0.01, compared to the control (with insulin and 2X amino acids but without drug).