Figure 4.

Effect of activated Gα_o on Ras-stimulated MAPK activity. CHO cells transfected in 6-cm dishes were serum starved for 18 h and assayed for MAPK activity as described in the legend to Figure 1. (A) Endogenous p42 MAPK activity in cells transfected with Gα_o-WT or Gα_o-Q205L (1.8 μg) and either empty vector or Ras-Q61L (2.2 μg). (B) HA-p44 MAPK activity in cells transfected with HA-p44 MAPK (1.4 μg), Gα_o-WT or Gα_o-Q205L (1.4 μg), and either empty vector or Ras-Q61L (1.4 μg). Data represent means ± SE of two separate experiments performed in duplicate. Expression of Ras-Q61L in the absence of exogenous Gα_o gave results similar to those obtained in cells transfected with the wild-type subunit.