The ferrous to ferric cycles in iron metabolism.
D000818:Animals; D001001:Anura; D002570:Ceruloplasmin / Q000378:metabolism; D005293:Ferritins / Q000378:metabolism*; D006454:Hemoglobins / Q000096:biosynthesis*; D007501:Iron / Q000378:metabolism*; D008099:Liver / Q000378:metabolism; D010088:Oxidoreductases / Q000302:isolation & purification; D014168:Transferrin / Q000378:metabolism*
D006454:Hemoglobins; D014168:Transferrin; D005293:Ferritins; D007501:Iron; D010088:Oxidoreductases; D002570:Ceruloplasmin