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Christensen JP, Cardin RD, Branum KC, Doherty PC.Christensen JP, et al. Among authors: cardin rd.Proc Natl Acad Sci U S A. 1999 Apr 27;96(9):5135-40. doi: 10.1073/pnas.96.9.5135.Proc Natl Acad Sci U S A. 1999.PMID: 10220431Free PMC article.