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Urban MO, Gebhart GF.Urban MO, et al. Among authors: gebhart gf.Proc Natl Acad Sci U S A. 1999 Jul 6;96(14):7687-92. doi: 10.1073/pnas.96.14.7687.Proc Natl Acad Sci U S A. 1999.PMID: 10393881Free PMC article.Review.