Effect of Loss of Bcl-x on cycle entry and apoptosis in BCR/ABL⁺ lymphoblasts. (A) Pleural effusion isolated from B-ALL and Bcl-x–deficient B-ALL mice 16 hours after BrdU injection. Cells were stained with fluorescently labeled antibodies against B220, CD19, and BrdU. Cell-cycle analysis, BrdU versus 7-AAD, is shown for the gated B220^dim, CD19⁺ population. Shown are representative results of 4 experiments. (B) Graph displaying difference in B220^dim, CD19⁺ S + G₂M status in either pleural effusion (PE) or spleen (SPL) cells isolated from B-ALL and Bcl-x–deficient B-ALL diseased mice (average ± SEM; n = 4 for PE and n = 3 for SPL). (C) Bone marrow, pleural effusion, and splenocytes isolated from B-ALL and Bcl-x–deficient B-ALL mice were stained with fluorescently labeled anti-B220, anti-CD19, and anti–annexin-V. Percentage of annexin⁺ cells are reported for B220^dim, CD19⁺ population only (results are given as means ± SEM; n = 4).