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Lehr HA, Frei B, Arfors KE.Lehr HA, et al. Among authors: arfors ke.Proc Natl Acad Sci U S A. 1994 Aug 2;91(16):7688-92. doi: 10.1073/pnas.91.16.7688.Proc Natl Acad Sci U S A. 1994.PMID: 7519784Free PMC article.