Ferritin is a cellular-storage protein with the main function of sequestering excess ferric iron and thus preventing high concentrations of soluble iron from becoming toxic to the cells. Dividing cells, both normal and neoplastic, have been shown to increase transferrm receptors in response to increase demand for iron, an essential micronutnent for cell division. However,if too much soluble iron is released into the cytoplasm of the cell,it will become toxic and damage or even kill the cell.Thus,ferrmn binds up the excess iron in order to prevent toxicity.