Activated M-Ras induces cytokine-independent proliferation. (A) BaF-3 transfected cells with empty vector (lane 1), wild-type M-Ras (lane 2), constitutively activated M-Ras/22Val (lane 3), M-Ras/22Lys (lane 4), or M-Ras/71Lys (lane 5) were lysed and analyzed by SDS-PAGE (14% acrylamide, 2 × 10⁵ cells per lane). M-Ras proteins were detected by immunoblotting. (B) Transfected BaF3 cells (10⁵ per well) were cultured with or without IL-3 (200 U/mL). Cells were counted and sequentially diluted as appropriate. The results represent the mean of 2 separate cultures that varied by less than 10%.