A prominent and conserved role for YY1 in Xist transcriptional activation

X-chromosome inactivation is a tightly regulated mechanism, which silences one of the two female X chromosomes. Here Makhlouf et al. show that the autosomal transcription factor YY1 directly promotes expression of the Xist RNA—a master regulator of X-chromosome inactivation—at the onset of the inactivation process.