Transgenic expression of human bcl-2 in STAT5aΔN^S711F-expressing HSCs restores peripheral myeloid expansion and lethality in transplant recipients. Mice that received a transplant as described in Figure 5 were analyzed 3 weeks after transplantation. Total WBC counts (A) and the absolute number of Gr-1⁺/Mac-1⁺ cells (B) are plotted for mice from 4 groups (for WBC: STAT5a^S711F vs STAT5aΔN^S711F, P < .01; STAT5a^S711F vs STAT5aΔN^S711F + bcl-2, P = .58; STAT5aΔN^S711F vs STAT5aΔN^S711F + bcl-2, P < .01; for Gr-1⁺/Mac-1⁺ cells: STAT5a^S711F vs STAT5aΔN^S711F, P < .01; STAT5a^S711F vs STAT5aΔN^S711F + bcl-2, P = .64; STAT5aΔN^S711F vs STAT5aΔN^S711F + bcl-2, P < .01; Student t test). Each dot represents an individual mouse. Horizontal bars indicate the average for all mice analyzed per group. (C) The survival of mice in each group was determined daily and deaths were recorded. The number of mice per group for all 3 panels was as follows: IR-GFP: n = 12; STAT5a^S711F: n = 12; STAT5aΔN^S711F: n = 12; STAT5aΔN^S711F + bcl-2: n = 12. IR denotes IRES-GFP vector and STAT5a^S711F denotes STAT5a^S711F-IRES-GFP vector. The white blood cell counts and flow cytometry were performed 20 to 24 days after transplantation for IR-GFP, STAT5a^S711F, and STAT5aΔN^S711F + bcl-2. Terminal analyses of STAT5aΔN^S711F-expressing mice were performed 2 to 3 months after transplantation.