Primary myelofibrosis (PMF) is a clonal myeloproliferative neoplasm (MPN) stemming from hematopoietic stem and progenitor cells (HSPCs), frequently associated with mutations in Janus kinase signal transducer (JAK2), calreticulin (CALR), or thrombopoietin receptor (MPL). Here, MPL is linked to primary myelofibrosis.