Expression of VpreB1 and ��5 in pro-B cells impairs their maturation.

IL-7 dependent pro-B cells were transduced with Bcl2 and either a VpreB1-IRES-��5-EGFP or an empty EGFP retroviral expression construct. B cell maturation was induced by culturing the transduced pro/pre-B cells without IL-7 for 5 or 7 days, as schematized in Figure 7. The maturation state of the B cells was determined by staining for surface ��LC by flow cytometry. The table shows the percentage of more mature ��LC positive and less mature ��LC negative cells within the VpreB1-IRES-��5-EGFP transduced or mock-transduced EGFP positive B cells.