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Gallagher MJ, Ding L, Maheshwari A, Macdonald RL.Gallagher MJ, et al.Proc Natl Acad Sci U S A. 2007 Aug 7;104(32):12999-3004. doi: 10.1073/pnas.0700163104. Epub 2007 Aug 1.Proc Natl Acad Sci U S A. 2007.PMID: 17670950Free PMC article.