Pathways of iron metabolism showing sites where HFE may play a role. The basic components of iron influx and efflux are shown in intestinal, erythroid, reticuloendothelial (RE), and parenchymal cells. Tf, transferrin; Cp, ceruloplasmin; Fe, iron; Heph, hephaestin; FT, ferritin; Hb, hemoglobin; HC, hemochromatosis.