Effect of CYT387 on cytokine concentrations during 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 serum was harvested from peripheral blood for cytokine analysis with a multiplexed 96-well ELISA-based assay. Bar graphs represent mean cytokine levels for: (A) VEGF (vascular endothelial growth factor), IFN-γ (interferon-γ), IL-3 and IL-17, (B) IL-9, LIF (leukocyte inhibitory factor) and IL-1β, (C) TNF-α (tumor necrosis factor-α), (D) IL-6, (E) IL-10, (F) G-CSF (granulocyte colony stimulation factor). Values represent mean ± SEM and *P ≤ .1 in a t test comparing normal mouse, 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 4.