Annexin V/PI analysis of CLL cells treated with PAS. Cells from patient AS31 with functional p53 (A) or patient AS32 with more than 97% p53 deletion (B) were treated with 0, 5, 10, 15, and 20 μM PAS for 24 hours. Apoptosis was quantified by annexin V/PI FACScan analysis. Values in each quandrant represent the percentage of gated cells in each quarter.