In fact, the prevention of thrombopoietin expression in a transgenic mouse model of PV [99] eliminated the PV phenotype [100], including splenomegaly, myelofibrosis, osteosclerosis, erythrocytosis, leukocytosis, and thrombocytosis, even though the JAK2 V617F mutation was still expressed. The gene discussed is JAK2; the disease is myelofibrosis.