Expression of BCR-ABL enhances differentiation of LT-HSCs. Analysis of LSK composition was performed in the BM and spleen isolated from 4-week-induced SCLtTA/BCR-ABL (dtg) and single transgenic (stg) controls. (A) For identification of LSK subpopulations, LT-HSCs (CD34⁻Flt3⁻), ST-HSCs (CD34⁺Flt3⁻), and MPPs (CD34⁺Flt3⁺) were further distinguished according to their immunphenotype. Depicted are the percentages of (B) LSK cells in BM and spleen, (C) LT-HSCs, (D) ST-HSCs, and (E) MPP cells within the LSK compartment. Error bars represent the mean ± SD. FSC indicates forward scatter; and SSC, sideward scatter. n = 4 per group. *P < .05. (F) Expression pattern of leukemic LSK cells was determined by microarray analyses of 3 leukemic dtg mice and 3 controls (wt or stg). The figure shows the clustering of the 6 mice according to 300 genes found to be at least 1.5-fold changed in expression (P < .05). The same clustering was achieved when unselected data were used or when the genes were analyzed using the SAM method. (G) A pathway analysis using Ingenuity software shows pathways with most significant changes in the LSK cell compartment of dtg mice.