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Stephenson K, Hoch JA.Stephenson K, et al.Proc Natl Acad Sci U S A. 2001 Dec 18;98(26):15251-6. doi: 10.1073/pnas.251408398. Epub 2001 Dec 4.Proc Natl Acad Sci U S A. 2001.PMID: 11734624Free PMC article.