Fig. 1.

Different subcultures of hESCs (HSF6 and H9) exhibit varied XCI status. (A–D) XIST RNA FISH signal (red) shows XIST RNA coating on the Xi. Immunostaining of hESCs with antibodies against H3K27me3 (red) (E–H), H4K20me1 (red) (I and J), and macroH2A1 (red) (K–M). Punctate XIST FISH signals and foci of H3K27me3, H4K20me1, and macroH2A1 stainings indicate the presence of an Xi. Please note that, for XIST− hESCs, the punctate staining pattern of H4K20me1 in some hESCs cannot be seen because of overexposure of the image to compensate for the weakly stained cells.