Prominent tipifarnib-induced inhibition of MAPK signaling. (A,C) after Jurkat cells were treated for 72 hours with the indicated tipifarnib concentration in the presence of 5μM Q-VD-OPh, whole cell lysates were subjected to immunoblotting with antibodies that recognize the indicate polypeptides. Ribosomal protein S6 and Hsp90 served as loading controls. (B) After Jurkat cells were treated for 72 hours with the indicated tipifarnib concentration in the presence of 5μM Q-VD-OPh, cDNA was prepared and RT-PCR was performed using primers specific for Bim.