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Strobel SA, Shetty K.Strobel SA, et al.Proc Natl Acad Sci U S A. 1997 Apr 1;94(7):2903-8. doi: 10.1073/pnas.94.7.2903.Proc Natl Acad Sci U S A. 1997.PMID: 9096319Free PMC article.