Tipifarnib-induced Bim up-regulation reflects inhibition of MAPK signaling. (A) After Jurkat cells were treated for 72 hours with 800nM tipifarnib or 20μM U0126, in the presence of 5μM Q-VD-OPh, whole cell lysates were subjected to immunoblotting with antibodies that recognize the indicated polypeptides. (B) After Jurkat cells were treated for 72 hours with 800nM tipifarnib or 20μM U0126, samples were stained with propidium iodide and subjected to flow microfluorometry. (C) After Jurkat cells and constitutively active MEK1 clones 10 and 12 were treated for 72 hours with diluent (−) or 800nM tipifarnib (+) in the presence of 5μM Q-VD-OPh, whole cell lysates were subjected to immunoblotting with antibodies that recognize the indicated polypeptides. (D) After the indicated clones were treated for 72 hours with diluent or 800nM tipifarnib, samples were stained with propidium iodide and subjected to flow microfluorometry. Error bars in panels B and D indicate mean ± SD of at least 3 independent experiments.