Changes in Ca2+ homeostasis are seen in reactive ineffective erythropoiesis (e.g. in β-thalassemia) (109) or in neoplastic erythropoiesis driven by Janus kinase 2 (JAK2) V617F mutation in polycythemia vera (PV) (110, 111). This evidence concerns the gene JAK2 and acquired polycythemia vera.