SRSF2 plays an unexpected role as reader of mC on mRNA, linking epitranscriptomics to cancer.

A common mRNA modification is 5-methylcytosine (mC), whose role in gene-transcript processing and cancer remains unclear. Here, we identify serine/arginine-rich splicing factor 2 (SRSF2) as a reader of mC and impaired SRSF2 mC binding as a potential contributor to leukemogenesis. Structurally, we identify residues involved in mC recognition and the impact of the prevalent leukemia-associated mutation SRSF2.