HAMP and nutritional disorder: Several inhibitors of hepcidin have been proposed: HIF-1a that is stabilised in hypoxia/iron deficiency, reduces hepcidin transcription by binding a HIF responsive element of hepcidin promoter53, the soluble variant of HJV downregulates hepcidin in vitro by competing with mHJV for the BMP ligand54, and matriptase 2 is a serin protease recently identified as a strong hepcidin inhibitor by cleaving membrane-HJV55.