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De Benedetti A, Pytel BA, Baglioni C.De Benedetti A, et al. Among authors: pytel ba.Proc Natl Acad Sci U S A. 1987 Feb;84(3):658-62. doi: 10.1073/pnas.84.3.658.Proc Natl Acad Sci U S A. 1987.Retraction in: Proc Natl Acad Sci U S A. 1987 Oct;84(19):6740. doi: 10.1073/pnas.84.19.6740.PMID: 2433688Free PMC article.Retracted.