SOAT1 and acquired polycythemia vera: The classical Philadelphia chromosome-negative MPNs include essential thrombocythemia (ET), polycythemia vera (PV), and primary myelofibrosis (PMF), which are characterized by driver mutations in a very limited number of phenotypic driver genes: JAK2, CALR, and MPL, involved in activation of the JAK-STAT signaling pathway [2].