JAK2 and myelofibrosis: The discovery of JAK2V617F (valine 617 to phenylalanine) mutation in myelofibrosis uncovers the activated JAK–STAT (signal transducer and activator of transcription) signaling as a primary driver for myelofibrosis, and supports the rationale for treating myelofibrosis by JAK2 inhibition [54].