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Dacey DM, Petersen MR.Dacey DM, et al.Proc Natl Acad Sci U S A. 1992 Oct 15;89(20):9666-70. doi: 10.1073/pnas.89.20.9666.Proc Natl Acad Sci U S A. 1992.PMID: 1409680Free PMC article.