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Forsberg K, Valyi-Nagy I, Heldin CH, Herlyn M, Westermark B.Forsberg K, et al.Proc Natl Acad Sci U S A. 1993 Jan 15;90(2):393-7. doi: 10.1073/pnas.90.2.393.Proc Natl Acad Sci U S A. 1993.PMID: 8380638Free PMC article.