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Blaser MJ, Kirschner D.Blaser MJ, et al. Among authors: kirschner d.Proc Natl Acad Sci U S A. 1999 Jul 20;96(15):8359-64. doi: 10.1073/pnas.96.15.8359.Proc Natl Acad Sci U S A. 1999.PMID: 10411880Free PMC article.