Nat. Chem. Biol. 6, 117–124 (2010); published online 10 January 2010; corrected after print 12 February 2010 and 2 March 2010

In the version of this article initially published, the structure of p110δ in complex with the inhibitor IC87114 was refined with an incorrect inhibitor structure (original Protein Data Bank accession code 2WXE). The structure has now been refined with the correct inhibitor structure and redeposited in the PDB with accession code 2X38. The structural image in Fig. 2a and the PDB accession code in the Methods section of the paper have been corrected in the HTML and PDF versions of the article.