Bcl-2 transgenic add-back increases the contribution of transplanted HSCs to the myeloid lineage. (A) STAT5ab^null/null FL cells at E14.5 and E15.5 were transduced with either MSCV/IRES-GFP vector control (IR), STAT5a^S711F, or STAT5aΔN^S711F and transplanted into lethally irradiated recipient mice. For the bcl-2 add-back, the STAT5ab^null/null mice were crossed with bcl-2 transgenic mice as stated in “In vivo complementation and transplantation.” STAT5ab^null/null bcl-2 transgenic FL cells were transduced with either IR-GFP or STAT5aΔN^S711F. (B) Representative flow cytometric plots show the accumulation of myeloid cells in the peripheral blood. The panels show the Gr-1⁺ or Mac-1⁺ cells co-gated for expression of GFP. The right panels show the percentage of Gr-1⁺Mac-1⁺ double-positive myeloid cells. The flow cytometry was performed 20 to 24 days after transplantation for all 4 groups.