Induction of hepatic Epo mRNA in IRP1^−/− mice is mediated by HIF2α. (A) Western blot analysis of IRP1 and β-actin in livers of 6-week-old WT and IRP1^−/− mice (n = 4). (B) Analysis of Epo mRNA expression by quantitative polymerase chain reaction in livers of 6-week-old WT IRP1^−/−, and IRP1^−/−:EPAS1^fl/^fl-Alb-cre mice (n = 6). *P < .05; ***P < .001.