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Zirwes RF, Schmidt-Zachmann MS, Franke WW.Zirwes RF, et al.Proc Natl Acad Sci U S A. 1997 Oct 14;94(21):11387-92. doi: 10.1073/pnas.94.21.11387.Proc Natl Acad Sci U S A. 1997.PMID: 9326619Free PMC article.