Hepcidin is regulated by erythropoietic activity, not anemia. Prior to phlebotomy (Phleb) mice were pretreated with NS (Phleb Alone), carboplatin (Cp + Phleb), doxorubicin (Dox + Phleb), or anti-EPO. Control mice (No Phleb) were pretreated with NS but did not undergo phlebotomy. (A) Hemoglobin concentration. (B) Reticulocyte fraction measured by flow cytometry. (C) Serum iron. (D) Hepcidin mRNA is the hepatic relative concentration normalized to the amount of β-actin relative to no phlebotomy samples. Means and SDs are shown, with superscripts indicating P < .001 compared to no phlebotomy by t test* or rank sum test^&; ^#P < .001 compared to phlebotomy alone by rank sum test, ^%P < .01 by rank sum test compared to no phlebotomy.