MIGRPax5A-transduced bone marrow cells successfully committed to the myeloid lineage but failed to expand to myeloid growth factors. Bone marrow stem cells were transduced with MIGR or MIGRPax5A and then cultured on OP9 stromal cells in 2 experiments according to the protocol described in Fig 5A. The absolute number of GFP⁺ gr-1⁺ cells (A) or F4/80⁺ cells (B) was normalized to the absolute number of Sca-1⁺/c-Kit⁺/Lin⁻ stem cells on day 6 to estimate the number of granulocytes or macrophages produced by a retrovirally transduced stem cell. Ten percent WEHI-3B conditioned media and 10 μmol/L ATRA were added on day 8 and 250 U/mL of muGM-CSF was added on day 11 to replicate the conditions of Fig 4 in which EML/Pax5A cells generated myeloid precursors that failed to expand.