Retroviral transduction of bone marrow stem cells with MIGRPax5A. (A) Bone marrow stem cells from 5-fluorouracil–treated mice were transduced with MIGRPax5A, a retrovirus that coexpresses BSAP/Pax5A with the GFP marker as a bicistronic message, and then analyzed by flow cytometry for GFP⁺ stem cells (c-Kit⁺/Sca-1⁺/Lin⁻). These stem cells were then differentiated as indicated and on days 6, 8, and 14. A small sample of cells was then removed from the culture and the numbers of myeloid cells were determined by flow cytometric analysis for granulocytes (Gr-1⁺) and macrophages (F4/80⁺). MIGR is the parental retrovirus of MIGRPax5A and expresses only the GFP marker. (B) Bone marrow stem cells were transduced with the MIGR retrovirus, cultured as described in (A), and then analyzed for the percentage of GFP⁺/Gr-1⁺ cells and GFP⁺/F4/80⁺ cells on days 8 and 14 by flow cytometry.