Effect of PFTα on apoptosis induction by p53-elevating agents. Cells from patient 19 were incubated in the absence of ZVAD with 10 μM nutlin 3a, 50 μM chlorambucil or 10 μM fludarabine. PFTα (25 μM) was added as indicated. Apoptosis was assessed by Western blot analysis of PARP cleavage (A) or by morphology (B). The densitometric intensity of the caspase 3–cleaved p85 PARP band is expressed as a ratio relative to the total intensity of the p85 and p116 (intact) bands. Note that the ability of PFTα to block p53-mediated transcription in cells from patient 19 is documented in Figure 3.