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Feng W, Hopper AK.Feng W, et al. Among authors: hopper ak.Proc Natl Acad Sci U S A. 2002 Apr 16;99(8):5412-7. doi: 10.1073/pnas.082682699.Proc Natl Acad Sci U S A. 2002.PMID: 11959996Free PMC article.