Fig 2: Loss of H3K9me3 correlates with impaired ATM activation in HGPS.(A). Representative fluorescence images of gammaH2AX and H3K9me3 in middle passage normal and HGPS fibroblasts after Dox treatment. “Low H3K9me3” is defined as any H3K9me3 fluorescence intensity that falls below the lower 5% of the normal population. Scale Bar: 5um. (B). Quantification of (A), showing the Spearman correlations between H3K9me3 green fluorescence intensity and gammaH2AX red fluorescence intensity in normal and HGPS fibroblasts. More than 100 cells were randomly picked for quantification in each group. (C). Western blotting analysis with anti-H3K9me3, anti-SUV39h1, anti-HP1alpha and anti-GAPHD antibodies on normal and HGPS fibroblasts at early, middle and late passages respectively. (D). Western blotting analysis with anti-pATM(S1981), anti-ATM, anti- gammaH2AX and anti-GAPDH antibodies on serum starvation synchronized normal and HGPS fibroblasts at early, middle and late passages after Dox treatment.