Nat. Biotechnol. 28, 935–942 (2010); published online 9 September 2011; corrected after print 7 December 2010 and 10 April 2012

In the version of this article initially published, Oliver Reubenacker should have been spelled Oliver Ruebenacker. In addition, the location of the author's affiliation is Farmington, not Storrs. The errors have been corrected in the HTML and PDF versions of the article.