Despite normal Bmp-Smad signaling in Bmp6^−/−-Tmprss6^−/− mice, hepcidin is not repressed in response to EPO. F2 littermates mice (CD1-C57BL/6 mixed background) of the different genotypes (5 to 9 mice per group) were injected or not with EPO and analyzed 15 hours later for (A) BM Erfe mRNA expression; and (B) liver Hamp mRNA expression. Results are expressed as mean ± SD and compared by ANOVA followed by Sidak’s multiple comparison tests. ****P < .0001; ***P < .001; **P < .01. Point estimates of the fold changes in gene expression (2^-ΔΔCt) are shown on the graphs. NS, non-significant.