Comparative effect of nutlin-3 and fludarabine on leukemic B-CLL cells and on normal BM clonogenic progenitors. (A) Positive and significant correlation between nutlin-3 and fludarabine cytotoxicity in B-CLL cultures (n = 29), measured after 48 hours of treatment. (B) Effect of nutlin-3 and fludarabine on normal clonogenic progenitors. Results are expressed as the mean of 3 independent experiments each performed in triplicate plus or minus SD of the number of colonies in the presence of 10 μM nutlin-3 or 10 μM fludarabine compared with the number in control cultures. Asterisk indicates significance at P < .01.