Figure 4.

Leptin (Lep) induces Akt and GSK3 phosphorylation but does not alter insulin-induced phosphorylation of the proteins. Cells were stimulated with 100 nM insulin (Ins), 60 nM leptin, or a combination of the two for the times indicated. Cells were lysed; the proteins were separated on SDS/12% PAGE and blotted with phosphoserine-specific Akt and GSK3 antibodies. Insulin and, to a lesser extent, leptin caused an increase in the phosphorylation of both proteins; the effect of the combination of the two hormones was identical of that of insulin alone. A representative Western blot of each is shown. The bar graphs represent the means of two or three independent experiments.