Figure 3.

PKCα-induced ERK activation and cell cycle arrest requires the activity of Ras.A, serum-starved IEC-18 cells were pretreated with vehicle (−) or 50 μM salirasib for 2 h, followed by 50 ng/ml EGF or 100 nM PMA for 10 min as indicated, and analyzed by Western blotting. B, cells were treated with PMA for 2 h in the absence or presence of salirasib and subjected to immunoblot analysis for the indicated proteins. C, N-Ras^−/−; H-Ras^−/−; K-Ras^f/f; Ubiq-Cre^ERT2 mESCs were treated with vehicle (−) or 1 μM 4-hydroxytamoxifen (4-OHT) for 7 days to knock out K-Ras and generate “Rasless” mESCs. The cells were then treated with 100 nM PMA or 20 μg/μl DiC₈ for 15 min as indicated, prior to Western blot analysis for PKCα, Ras, pERK, and pRSK. The data are representative of three independent experiments. mESC, mouse embryonic stem cell; PMA, phorbol 12-myristate 13-acetate.