Homeostasis of hepcidin regulation. The schema of hepcidin regulation in hepatocytes as described in the text. The involved proteins enable nuanced regulation of hepcidin expression in light of hepcidin's central role in iron homeostasis. In β-thalassemia, one or multiple mechanisms involved in hepcidin stimulation are altered, resulting in hepcidin suppression relative to the degree expected from concurrent iron overload. The erythroid regulator probably has an effect through one or multiple mechanisms involved in hepcidin regulation. BMPR I/II indicates BMP receptors type I and II; Smad-P, phosphorylated Smad complex; HFE, hemochromatosis protein; and TMPRSS6, transmembrane serine protease matriptase-2.