Effects of U0126 or FTI-277 treatment for 36 hours on the cell-cycle–dependent activation of MEK-1/2.

NB-4 cells were incubated in the absence or the presence of 50 μM U0126 or 20 μM FTI-277. After 36 hours, double staining with propidium iodide and an antibody specific for activated PP-MEK-1/2 was performed as described in “Materials and methods.” Representative cell-cycle profiles (left) and FACS profiles of the double staining (right) are shown. (A) Untreated NB-4 cells; (B) solvent-treated (DMSO) NB-4 cells; (C) NB-4 cells treated with 20 μM FTI-277; (D) NB-4 cells treated with 50 μM U0126. NB-4 cells treated with FPT-3 are not shown because of nearly complete apoptosis at this time point.