We assayed the multicopper ferroxidase1 activity in iron-deficient cells and observed that concomitant treatment with 8 μM CO significantly increased the activity of multicopper ferroxidase1 as compared to the treatment of iron-deficiency alone (Fe0.1, control) (Figure 5a), consistent with the data of fox1 transcript (Figure 4a). Here, RBFOX1 is linked to Iron deficiency anemia.