HO-1^−/− reticulocytes express more TfR at the cell membrane, have higher iron uptake, and exhibit decreased levels of phosphorylated eIF2α. Wild-type (HO-1^+/+) and HO-1 knockout (HO-1^−/−) mice were injected with phenylhydrazine (25 mg/kg) for 3 consecutive days. After 2 days of rest, reticulocytes from HO-1^+/+ and HO-1^−/− mice were collected. (A) Flow cytometry analysis showing cell-membrane TfR levels of reticulocytes HO-1^+/+ and HO-1^−/− reticulocytes. (B) HO-1^+/+ and HO-1^−/− reticulocytes were incubated with ⁵⁹Fe-Tf for 15 minutes, after which heme and non-heme fractions were isolated. (C) Representative western blot showing TfR, eIF2α-P, and globin protein levels of HO-1^+/+ and HO-1^−/− reticulocytes. Error bars of graphs represent standard deviation of 3 independent experiments (n = 3). *P < .05; **P < .001.