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Roper RJ, Baxter LL, Saran NG, Klinedinst DK, Beachy PA, Reeves RH.Roper RJ, et al.Proc Natl Acad Sci U S A. 2006 Jan 31;103(5):1452-6. doi: 10.1073/pnas.0510750103. Epub 2006 Jan 23.Proc Natl Acad Sci U S A. 2006.PMID: 16432181Free PMC article.