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Sparrow LG, Metcalf D, Hunkapiller MW, Hood LE, Burgess AW.Sparrow LG, et al. Among authors: metcalf d.Proc Natl Acad Sci U S A. 1985 Jan;82(2):292-6. doi: 10.1073/pnas.82.2.292.Proc Natl Acad Sci U S A. 1985.PMID: 3871523Free PMC article.