JAK2 and myeloproliferative neoplasm: Logically, numerous inflammatory cytokines are overexpressed by MPN patients; some activate the JAK2/STAT5 pathway (G-CSF, GM-CSF, interleukin 6 (IL-6)) and further increase myelopoiesis, while others activate the JAK1/STAT1-STAT3 pathways (IL-6, interferons (IFN)) and thus enhance cytokine production and facilitate cell survival (13–19).