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Gupta RS, Aitken K, Falah M, Singh B.Gupta RS, et al.Proc Natl Acad Sci U S A. 1994 Apr 12;91(8):2895-9. doi: 10.1073/pnas.91.8.2895.Proc Natl Acad Sci U S A. 1994.PMID: 8159675Free PMC article.