Thus, JAK2/STAT signaling pathway plays a central role in the MPN pathophysiology5 and has been targeted by ruxolitinib, a selective JAK1/2 inhibitor approved for the treatment of intermediate and high-risk PMF and PV patients that provides some clinical benefits, but does not lead to complete remission of these diseases and fails to eliminate the malignant clone6–9. Here, JAK2 is linked to acquired polycythemia vera.