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Samples in periodicals archive:
Herzing LB, Romer JT, Horn JM, Ashworth A (1997). "Xist has properties of the X-chromosome inactivation centre". Nature 386 (6622): 272–5. doi:10. 1038/386272a0. PMID 9069284.
Xist (X-inactive specific transcript) is an RNA gene on the X chromosome of the placental mammals that acts as a major effector of the X inactivation process.  It is a component of the Xic - X-chromosome inactivation centre - along with two other RNA genes (Jpx and Ftx) and two protein genes (Tsx and Cnbp2).  The Xist RNA, a large (17 kb in humans) transcript, is expressed on the inactive chromosome and not on the active one.