Effect of CYT387 on hematopoietic cell lineages in MPN in vivo. Balb/c mice were subjected to bone marrow transplantation with bone marrow donor cells retrovirally transduced to express JAK2^V617F. Thirty-four days after transplantation, mice exhibited symptoms of MPN as measured by elevated white blood cell counts and hematocrit. Mice were divided into 3 groups and initiated on twice daily oral gavage administration of vehicle control, 25 mg/kg CYT387, or 50 mg/kg CYT387 (n = 12 per group). At day 83 after bone marrow transplantation, all mice were sacrificed and spleen and bone marrow cells were stained with fluorescently conjugated antibodies specific for: (A) Gr1 (Granulocytes), (B) CD19/B220 (B cells) and CD3 cells (T cells), (C) CD71 (early erythroid progenitors) and Ter119 (late erythroid progenitors), (D) cKit⁺CD34⁻ (stem cells/early progenitors) and cKit⁺CD34⁺ (late progenitors), (E) CD41 (megakaryocytes). Values represent mean ± SEM and *P < .05 in a t test comparing 25 mg/kg or 50 mg/kg treatment groups with the 0 mg/kg vehicle control. A complete list of numerical values and statistical analyses is found in supplemental Table 2. Representative dot plots are found in supplemental Figure 4.