The EPO-induced increase in spleen size was clearly dependent on iron availability, as the spleens from EPO-treated mice kept on low-iron diet were significantly smaller than spleens from EPO-treated mice kept on control diet (Fig 5E); nevertheless, the EPO-induced increase in splenic Fam132b mRNA and Tfr2 mRNA content was not influenced by iron deficiency (Fig 5F and Fig 4F). This evidence concerns the gene ERFE and Iron deficiency anemia.