Effect of PFTα on nutlin-induced transcription of p21^CIP1 and Puma. Cells from patient 19 (A) or from patient 23 (B) were incubated in media containing 100 μM ZVAD. Nutlin 3a (10 μM) and 25 μM PFTα were added as indicated. Whole cell lysates were prepared (“Methods”) and analyzed by Western blotting. Lysates from patient 25 were analyzed on the same blot with patient 23 lysates to provide a positive control for the p53 antibody. Expression levels of the p53 targets p21CIP1 and PUMA were quantified by densitometry. The band intensities were normalized with respect to Bcl-2 band intensities, since expression of Bcl-2 has been shown to be extremely stable in CLL cells.³⁸