Nature Reviews Genetics 13, 77–83 (2012)

In two instances in the same sentence of the above article, the use of 'mRNA' and 'microRNA (miRNA)' had been reversed. The sentence should read: “Although the direct pairing of an miRNA with its target mRNA cannot yet be deduced from these data, the detection of Argonaute binding sites in both miRNAs and mRNAs enabled the discovery of endogenous mRNA target sites.” The article has been corrected online. The editors apologize for this error.