Cytokine and leukemia stimulation of BM-ECs triggers the mTOR pathway. Quiescent BM-ECs were stimulated and analyzed for activation of mTOR downstream substrates (S6RibP, 4E-BP1) and activation of Akt/PKB by Western blot. (A) BM-ECs cultured overnight in EBM + 1% FBS were stimulated for 15 and 30 minutes with a cocktail of proangiogenic cytokines (FGF-2, VEGF, IGF-1, and EGF). Data are representative of 2 BM-EC donors tested and 2 independent experiments. (B) Cells were cultured overnight in EBM2 and stimulated for 15 minutes with 10% vol/vol of plasma from leukemia patients. The arrow indicates the correct band. Three representative cases of 7 patients tested.