Suppression of DNA damage–induced p53 accumulation and cell death in primary BCP-ALL cells by cAMP. (A) BCP-ALL cells isolated from bone marrow aspirates of 3 patients with pediatric BCP-ALL (ALL 1, ALL 2, and ALL 3) were treated with or without forskolin for 30 minutes before irradiation with 2 Gy. After 18 hours of incubation, cell death was assessed by costaining the cells with FITC-conjugated anti-CD19 antibodies and PI and analyzing PI uptake in the CD19⁺ subpopulation. (B) A portion of ALL cells in panel A were harvested 4 hours after IR treatment and subjected to Western blot analysis with p53 and actin antibodies. (C) ALL 1 cells were treated with or without forskolin for 30 minutes before addition of doxorubicin or 4-OOH-CP. Cells were then cultured for 18 hours before costaining with FITC-conjugated anti-CD19 antibodies and PI followed by FACS analysis as described in panel A. (D) ALL 3 and ALL 2 cells were treated with or without forskolin for 30 minutes before addition of doxorubicin or 4-OOH-CP, respectively. After 4 hours, cells were harvested and subjected to Western blot analysis with the indicated antibodies. Vertical lines have been inserted to indicate repositioned gel lanes.