Additional circumstantial evidence for this hypothesis has come from a number of sources, including (1) expression of c-Mpl on human HSCs [43], the cell of origin of MPNs; (2) aberrant expression of wild-type c-Mpl in mice induces an MPN [53]; and (3) c-Mpl is overexpressed on the neoplastic cells of about half of patients with acute myelogenous leukemia and myelodysplastic syndromes [54]. Here, MPL is linked to myeloproliferative disorder.