Induction of apoptosis in primary CLL cells with forodesine. When CLL cells were incubated with forodesine at different time points, there was induction of apoptosis that was measured by PARP cleavage, and the Western blots were normalized to actin. Data from 2 patients (no. 1 in A; no. 4 in B) are provided. The immunoblots of PARP for 5 patients were quantitated using densitometer and the cleaved PARP was correlated with the dGTP accumulation, and the relationship between accumulation of dGTP and the PARP cleavage for 5 patients at different time periods (4, 6, and 8 hours) are plotted (C).