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Jansen S, Baas P, Gasson P, Lens F, Smets E.Jansen S, et al.Proc Natl Acad Sci U S A. 2004 Jun 8;101(23):8833-7. doi: 10.1073/pnas.0402621101. Epub 2004 May 26.Proc Natl Acad Sci U S A. 2004.PMID: 15163796Free PMC article.