JAK2 and acquired polycythemia vera: Ten weeks after tamoxifen induction, recipient mice that received transplantation with LSL-Jak2-V617F; CreERT2T/+ BM (hereafter, termed as mice with PV) exhibited a classic PV phenotype with elevated red cell count, reticulocytes, hematocrit and hemoglobin levels; decreased mean corpuscular hemoglobin (MCH) and mean cell volume (MCV); suppressed renal erythropoietin (Epo) expression; and splenomegaly (Figure 3B-I); the severity of the phenotype was not inconsistent with human disease.