Nat. Struct. Mol. Biol. 14, 1229–1230 (2007); published online 18 November 2007; corrected after print 18 December 2007

In the version of this article initially published, the “Accession codes” section was missing. The section should read:

Accession codes. Protein Data Bank: Coordinates and structure factors have codes 2PQW, 2RJE and 2RJF (L3MBTL1–H4K20me2 complexes), 2RJD (L3MBTL1 apo structure) and 2RJC (L3MBTL1–MES complex).

The error has been corrected in the HTML and PDF versions of the article.