EPO and microcytic anemia: Serum EPO levels were inappropriately low in both Col4a3KO and CPD mice (Fig. 3d), and despite increases in circulating iron and iron stores, CPD mice showed a similar degree of microcytic anemia as Col4a3KO, assessed by reduced hemoglobin, red blood cell number, hematocrit and mean corpuscular volume (Fig. 3f–h).