SLC40A1 and Iron deficiency anemia: Furthermore, expression of TfR1 mRNA was upregulated (Figure 3O) and Slc40a1 mRNA was downregulated (Figure 3P) in Hampfl/fl;Myh6.Cre+ and Slc40a1 C326Yfl/fl;Myh6.Cre+ hearts relative to their respective controls, consistent with a transcriptional response to intracellular iron deficiency (Rouault and Klausner, 1997; Rouault, 2006; Ward and Kaplan, 1823).