KY1070 in combination with EPO increases FPN expression on erythroid progenitor cells in the bone marrow and reduces high intracellular free iron levels. (A) Liver Hamp mRNA levels in iron-treated mice receiving either IgG4 isotype control (3 mg/kg n = 7), KY1070 (3 mg/kg; n = 8), EPO (10 µg/kg; n = 6), or both (n = 6) twice. (B) Densitometric quantification of FPN protein expression of erythroid precursor cells in the bone marrow. (C) Calcein fluorescence in erythroid bone marrow progenitors was measured by flow cytometry. Graphs show MFI (mean fluorescence intensity) values of individual erythroid precursor populations (basophilic cells [I], polychromatic cells [II], and orthochromatic cells and reticulocytes [III]; for gating strategy; see supplemental Figure 13C). Two-way ANOVA with Tukey corrected post hoc Student t test for multiple comparisons between all groups was applied. Results are shown as means ± SEM. Significant levels are indicated for the iron + Isotype–treated control group against all treatment groups and iron + EPO vs iron + KY1070 + EPO–treated rodents. *P < .05; **P < .01; ***P < .001.