FIG. 8.

Insulin-dependent Ras function in L6 cells. (Top) L6hIR2 cells were treated with lovastatin or transfected with the dominant negative L61,S186 Ras mutant and/or exposed to LY379196 as indicated. The cells were then stimulated with insulin or EGF (100 nM) and solubilized, and the Ras GTP loading was estimated by the GTP overlay assay as described in Materials and Methods. Overlay filters were autoradiographed, and GTP loading was quantitated by densitometry. (Bottom) The cell lysates were precipitated with MAPK antibody, and MAPK activity was assayed as described in the legend to Fig. 4. Bars represent the means ± standard deviations of duplicate determinations in four (top) and three (bottom) independent experiments.