JAK2 and myeloproliferative neoplasm: Overall, this study describes three preclinical models of MPN, recapitulates changes induced by a JAK2 inhibition and finally suggests that it could (i) prevent the development of fibrosis if applied in early-phases, (ii) normalize platelet count and (iii) reduce splenomegaly through reduction in stem cell mobilization from the marrow to the spleen.