JAK2 and myelofibrosis: The identification of the JAK2V617F mutation has spurred the discovery and development of JAK inhibitors for the treatment of MPNs [24], and the JAK1/JAK2 inhibitor ruxolitinib received regulatory approval for the treatment of myelofibrosis, and for PV patients who are resistant to or intolerant of hydroxyurea [25–27].