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Bulyk ML, Huang X, Choo Y, Church GM.Bulyk ML, et al.Proc Natl Acad Sci U S A. 2001 Jun 19;98(13):7158-63. doi: 10.1073/pnas.111163698. Epub 2001 Jun 12.Proc Natl Acad Sci U S A. 2001.PMID: 11404456Free PMC article.