Ferroportin is a transmembrane protein that transports iron from the inside of a cell to the outside of it. Recent research suggests that ferroportin is inhibited by hepcidin, which therefore is the "master regulator" of human iron metabolism. Hepcidin binds to ferroportin, and results in the internalisation of ferroportin within the cell, followed by degradation by the proteasome. This results in retention of iron within the cell, and a reduction in iron levels within the plasma. This is part of the mechanism that causes anaemia of chronic disease; hepcidin is released from the liver in response to inflammatory cytokines, namely interleukin-6, which results in an increased hepcidin concentration and a consequent decrease in plasma iron levels.