Additional file 2. Immunofluorescence (IF) detects H3K9 methylation on the inactive X chromosome. (a) Representative images showing IF staining for DAPI (grey), H3K9me2 (blue) and as a marker of the Xi Smchd1 (green), in MEFs. A representative histogram showing pixel intensity along a cross-section of the displayed cell is also shown. (b) As for a, but showing H3K9me3 (pink). The percentage of cells showing overlap in the pixel traces between histone marks and Smchd1 is also shown, as well as p-values determined by Chi2 test.