For example, the overexpression of NFE2 was described in patients with PV and not in patients with ET [77], while high expression of the proteins HSP70 and calreticulin in the membrane of erythrocytes of patients with PV compared with patients with ET suggested an important role for these factors in the proliferation and erythroid function of PV, respectively [78,79]. Here, CALR is linked to acquired polycythemia vera.