EPO suppresses BMP target genes in an ERFE-dependent manner. (A-B) WT and Erfe KO male mice (10 to 13 weeks old) were injected with 3 doses of 200 IU EPO or vehicle (Veh) at 1 dose every 24 hours and were analyzed 24 hours after the last injection to measure expression of BMP-target genes in the liver (A) and serum and liver iron (Fe) (B). (C-D) Nine-week-old WT male mice were injected intravenously with 200 µg of murine Erfe or a clipped (inactive) version of the protein as a control (Ctrl). Mice were analyzed 3 hours after the injections to measure serum and liver iron (C) and expression of BMP-target genes, Bmp2 and Bmp6 in the liver (D). Bars represent mean ± standard deviation. Gene expression represented as −ΔCT, calculated as the threshold cycle (CT) for the gene of interest minus the reference gene (Hprt). Threshold set as 0.2. n = 6-8 mice per group. *P < .05; **P < .01; ***P < .001; ****P < .0001 using 1-way analysis of variance followed by Tukey test for multiple comparisons (A-B) or Student t test (C-D).