Western blot analysis of PARP cleavage in CLL cells. Cells from CLL 21 (A) or CLL 17 (B) were incubated for 18 hours with the indicated additions. IL-4 was added at 10 ng/mL and PF-956980 at 1μM. Lysates were analyzed by Western blotting. PARP cleavage was quantified by dividing the densitometric band intensity of the 85-kDa band by the total intensities of the 116- and 85-kDa bands. The data are representative of 10 experiments.