JAK2 and primary myelofibrosis: Ruxolitinib therapy can limit further bone marrow fibrosis in JAK2 p. V617F-driven MF and PV (Verstovsek et al., 2017b; Kroger et al., 2021) and multiple studies have shown that ruxolitinib therapy correlates with improved overall survival (Verstovsek et al., 2012a; Vannucchi et al., 2015a; Bose and Verstovsek, 2020; Kroger et al., 2021).