Ruxolitinib, a typical JAK1/2 inhibitor, was used to provide systemic symptom relief in post-PV myelofibrosis (PPMF) (Verstovsek et al., 2012) and chronic-phase PV (Vannucchi et al., 2015; Passamonti et al., 2017), while did not promote apoptosis of hematopoietic stem cells (HSCs) and failed to achieve molecular remissions (Wang et al., 2014). Here, JAK1 is linked to acquired polycythemia vera.