Progression to blast crisis is accompanied by changes in the frequency and function of hematopoietic stem and progenitor cells. (A) The size/composition of the HSC (LSK) compartment between CML and BC mice (n = 18 for both groups), the myeloid progenitor compartment, including the GMP fraction (n = 16 for both groups) and the Lin−IL7R+ lymphoid progenitor cell (n = 18 for BC and CML and n = 17 for age-matched WT mice) compartments were assessed by flow cytometry. Student’s t test was used. (B) Representative FACS plots of the myeloid progenitor and GMP compartments between BC and SB mice. (C) Mean colony numbers for BC (n = 16), CML (n = 15), and age-matched WT (n = 11) mice in serial replating assays. Student’s t test was used. (D) Kaplan-Meier curves of secondary transplants of BC (n = 20) and CML (n = 25) cases into NOD-SCID recipients (P < 0.05). Log-rank test was used. Data are representative of at least three independent experiments. Data are mean ± SEM. *, P < 0.05; **, P < 0.01; ***, P < 0.0001.