LRPAP1 and Iron deficiency anemia: We also found that, similar to the effect of iron deficiency, RBCs from RAP-KO embryos were smaller than those from littermate controls (92.8 vs 106 fL, p < 0.05) and had less total hemoglobin (24.0 vs 28.5 pg/cell, p < 0.0001) (Figure 4B).