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Levitz SM, Nong S, Mansour MK, Huang C, Specht CA.Levitz SM, et al.Proc Natl Acad Sci U S A. 2001 Aug 28;98(18):10422-7. doi: 10.1073/pnas.181331398. Epub 2001 Aug 14.Proc Natl Acad Sci U S A. 2001.PMID: 11504924Free PMC article.