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Cotton JA, McInerney JO.Cotton JA, et al.Proc Natl Acad Sci U S A. 2010 Oct 5;107(40):17252-5. doi: 10.1073/pnas.1000265107. Epub 2010 Sep 17.Proc Natl Acad Sci U S A. 2010.PMID: 20852068Free PMC article.