Translational de-repression of HIF2α mRNA in IRP1^−/− kidneys. WT, IRP1^−/−, and IRP2^−/− mice were euthanized at the age of 6 weeks. RNA was prepared from kidneys and analyzed by sucrose gradient fractionation. (A) A typical kidney polysomal profile from 6-week-old mice. Pooled monosomes (fractions 9 and 10) and polysomes (fractions 12-17) are shown. (B) Distribution of HIF2α mRNA, H-ferritin (FTH) mRNA, and 18S rRNA among monosomal and polysomal fractions. Relative quantities of target genes were normalized to the internal control β-actin that was then normalized to the level of input mRNA. Data were obtained from n = 6 mice. ***P < .001.