Effect of the combination of fludarabine with mitoxantrone and/or mafosfamide on p53 and Mcl-1 levels. Cells from patients no. 2, 3, and 17 were incubated for 48 hours with fludarabine (F; 1 μg/mL), mitoxantrone (M; 0.5 μg/mL), and/or mafosfamide (Mf; 1 μg/mL). Cell viability was determined by the MTT assay as described in Materials and Methods and is expressed as the percentage with respect to control cells. Western blots of p53 and Mcl-1 were quantified and the values are expressed as the percentage with respect to control cells (Mcl-1) or cells incubated with the 3 drugs (p53). Similar p53 levels were obtained for the 3 patients.