The recent discovery of reversible mRNA methylation has opened a new realm of post-transcriptional gene regulation in eukaryotes. The identification and functional characterization of proteins that specifically recognize RNA N 6-methyladenosine (m 6 A) unveiled it as a modification that cells utilize to accelerate mRNA metabolism and translation. N 6-adenosine methylation directs mRNAs to distinct fates by grouping them for differential processing, translation and decay in processes such as cell differentiation, embryonic development and stress responses. Other mRNA modifications, including N 1-methyladenosine (m 1 A), 5-methylcytosine (m 5 C) and pseudouridine, together with m 6 A form the epitranscriptome and collectively code a new layer of information that controls protein synthesis.