Figure 8.

PTEN inactivation and Rac are upstream of MRLC phosphorylation. (a) Effect of the Rac inhibitor (NSC23766) on the lepin-induced increase of MRLC phosphorylation. Cells were treated with leptin or leptin and 50 μM NSC23766 for 30 min prior to western blot analysis. The relative ratio of phosphorylated MRLC to total MRLC was plotted based on the quantification of the band intensities. The data are expressed as the mean±s.e.m. (n=3). *P<0.05 compared as indicated. (b) The change in MRLC phosphorylation by PTEN inactivation. The cells were transfected with PTEN^WT (wild-type PTEN) or PTEN^C124 construct (a lipid and protein phosphatase dead form of PTEN) for 48 h. The relative ratio of phosphorylated MRLC to total MRLC was plotted based on the quantification of the band intensities. The data are expressed as the mean±s.e.m. (n=3). *P<0.05 compared as indicated. (c) Schematic illustration of signaling pathways underlying K_ATP channel trafficking induced by GD or leptin revealed by the present and previous studies.^{2, 4, 31}