G Immunofluorescence staining against pRH5 and 2a2iL-RH5 (46, XX) for H3K27me3. Nuclei were stained with 4′, 6-diamidino-2-phenylindole (DAPI). Reactivation of inactive X-chromosome in female 2a2iL-RH5 was confirmed by the lack of H3K27me3 nuclear foci. Scale bar: 50 µm. 