Bcl-2 expressing pre-B cells do not generate B-ALL. (A) Expression of Bcl-2 relative to β-Actin was assessed by qPCR in pro-B and pre-B cells isolated from the bone marrow of wild-type mice (n = 4). Reactions for each population were run 4 times. (B). Pro-B and pre-B cells were isolated from the bone marrow of wild-type or Eμ-Bcl2-22 transgenic mice and 25 000 cells were seeded in duplicate in wells of 6-well culture plates. Photomicrographs of cells after 10 days in culture are shown (bar represents 50 μm). (C) Total number of cells per well from cultures shown in panel B. (D) Pro-B cells, but not pre-B cells, from wild-type and Eμ-Bcl2-22 mice generated B-ALL. Cells were manipulated as described in Figure 1A. The indicated populations were sorted from pools of bone marrow from 4 wild-type and 4 Eμ-Bcl2-22 mice, respectively. Each cell population was transduced as described in supplemental Figure 2 and injected into 4 recipient mice.