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Chen L, Marquardt ML, Tester DJ, Sampson KJ, Ackerman MJ, Kass RS.Chen L, et al. Among authors: sampson kj.Proc Natl Acad Sci U S A. 2007 Dec 26;104(52):20990-5. doi: 10.1073/pnas.0710527105. Epub 2007 Dec 19.Proc Natl Acad Sci U S A. 2007.PMID: 18093912Free PMC article.