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||p.1239 right column bottom paragraph:"One idea has been that perhaps there is a metabolically stable, nucleus-restricted poly(A) RNA population that helps to organize and structurally define certain nuclear bodies such as speckles (Fakan et al., 1984 Huang et al., 1994 Lamond and Spector, 2003). This idea stems from observations that as much as 30% of the poly(A) RNA never leaves the nucleus in growing mammalian cells (primary sources). At least some of this poly(A) RNA consists of noncoding sequences that seem to have a variety of nuclear functions (Morey and Avner, 2004)."