Figure 6. Myc-induced B-cell transformation occurs with developmental blocks at comparable stages in both wild-type and Stat5-deficient leukemia.

E14.5 fetal liver cells (Eμ-Myc/H2K-Bcl-2 or Eμ-Myc/H2K-Bcl-2/Stat5ab^null/null) on the C57BL/6 background obtained from timed matings as described in Supplementary Figure S2 were transplanted into lethally irradiated BoyJ recipient mice at the ratio of 1 donor fetal liver to 5 recipient mice. Four weeks after the fetal liver transplantation, mouse peripheral blood was analyzed for B-cell development with CD4, CD19, CD43, B220, and donor-specific CD45.2 antibodies. A. Representative histograms are shown from 5 mice of either Eμ-Myc/H2K-Bcl-2 or Eμ-Myc/H2K-Bcl-2/Stat5ab^null/null fetal liver transplanted mice. Gating strategy on live cell populations; Eμ-Myc/H2K-Bcl-2 fetal liver cells mainly showed pro-B phenotypes (CD4⁻Cd19⁺Cd43⁺B220⁺) and Eμ-Myc/H2K-Bcl-2/Stat5ab^null/null showed either pre-pro-B (CD4⁺CD19⁻CD43⁺B220⁺) or mixed pre-pro-B and pro-B phenotype. B. Representative histogram from a separate experiment from 4 Eμ-Myc/H2K-Bcl-2 or 3 Eμ-Myc/H2K-Bcl-2/Stat5ab^null/null fetal liver transplanted mice. Eμ-Myc/H2K-Bcl-2 fetal liver cells showed mixed pre-pro-B and pro-B phenotype while Eμ-Myc/H2K-Bcl-2/Stat5ab^null/null mice had mainly pro-B phenotypes.