Modulation of Erfe, hepcidin, and Id1 by EPO in iron-loaded mice. Sv129 WT mice were injected with iron dextran and challenged with EPO or vehicle 1 week later. Control mice (no iron) were treated with saline. Non-heme LIC (A) was measured in untreated and iron-loaded mice. Erfe expression was measured by qRT-PCR in BM-derived cells. mRNA expression was normalized relative to the erythroid marker GypA (B). Four mice per group were analyzed. Bmp6 mRNA expression (C), BMP-SMAD target genes as Hamp (D), and Id1 (E) were analyzed by qRT-PCR in total liver of treated animals and normalized to the housekeeping gene Hprt1. Error bars indicate ± SEM. *P < .05; **P < .01; ***P < .001; ****P < .0001. ns, nonsignificant.