The Discovery of 5‐Formylcytosine in Embryonic Stem Cell DNA

Touching base: Sophisticated mass spectrometry has shown that 5-formylcytosine is a constituent of mammalian embryonic stem cell DNA. This base is likely produced from methylcytosine via hydroxymethylcytosine (see scheme), and it may serve as an intermediate in the long searched for pathway of active DNA demethylation. Detailed facts of importance to specialist readers are published as "Supporting Information". Such documents are peer-reviewed, but not copy-edited or typeset. They are made available as submitted by the authors. Please note: The publisher is not responsible for the content or functionality of any supporting information supplied by the authors. Any queries (other than missing content) should be directed to the corresponding author for the article.