Differential silencing of X-linked genes upon ectopic Xist RNA coating in differentiating X∆TsixY vs. X∆TsixX EpiSCs. Boxplots of expression of the nine X-linked genes surveyed as in Fig. 2 in individual nuclei of differentiating XY, XX, X∆TsixY, and X∆TsixX EpiSC lines (lines 2, 2, 4, and 5, respectively; all EpiSC lines from Fig. 3, with the exception of X∆TsixX EpiSC line 2). d, day. n = 100 nuclei per cell line per day of differentiation for each class of Xist RNA-coated cells. *P < 10−6, significant difference in gene expression between X∆TsixY and X∆TsixX nuclei; Welch’s two-sample T test. X-linked gene expression does not significantly differ between X∆TsixY and X∆TsixX nuclei lacking ectopic Xist coats (P > 0.2). Related data are included in SI Appendix, Figs. S5–11.