Is erythroferrone finally the long sought-after systemic erythroid regulator of iron?

Iron metabolism is regulated on the cellular and the systemic level. Over the last decade, the liver peptide "hepcidin" has emerged as the body's key irons store regulator. The long postulated "erythroid regulator of iron", however, remained elusive. Last year, evidence was provided, that a previously described myokine "myonectin" may also function as the long sought erythroid regulator of iron. Myonectin was therefore re-named "erythroferrone". This editorial provides a brief discussion on the two functions of erythroferrone and also briefly considers the emerging potential role of transferrin receptor 2 in erythropoiesis.