A mild decrease in ferritin, and potentially transferrin, in the absence of erythroid Arg1 in RBC Arg1 KO mice suggests a role for Arg1 in iron handling, warranting further investigation of the potential role of Arg1 under conditions such as iron-deficiency anemia, altered erythropoiesis, infection, or chronic inflammatory states, where the effects may be more pronounced. The gene discussed is TF; the disease is anemia.