This confirms a central role for MPL in this transgenic mouse model of PV, and indicates that the lower plasma THPO level compared to the wild-type mouse was due to increased THPO consumption by the JAK2V617F-mediated expansion of the megakaryocyte and circulating platelet pools, a feature also seen with MPL and CALR mutations [56]. This evidence concerns the gene CALR and acquired polycythemia vera.