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. 2008 Jul 10;7:61. doi: 10.1186/1476-4598-7-61

Figure 2.

Figure 2

Overexpression of H2AX but not H2A leads to apoptotic cell death and stimulates apoptosis. (A) Quantification of apoptotic U-2 OS cells following transient overexpression of empty GFP vector, GFP-H2AX or GFP-H2AX-SA for 24 h. Only transfected, GFP-positive cells were counted. Apoptosis was scored based on the nuclear morphology. Each bar indicates mean + standard error of at least three independent experiments with at least 100 cells counted per experiment. (B) Fluorescence microscopic analysis of U-2 OS cells transiently transfected with empty GFP vector (control), GFP-H2AX or GFP-H2AX-S139A for expression of γ-H2AX. Note the negative staining for γ-H2AX of a cell transfected with mutant H2AX-S139A. Nuclei stained with DAPI. Scale bar indicates 10 μm. (C) Quantification of apoptotic cells in U-2 OS populations stably transfected with empty GFP vector, GFP-H2AX or GFP-H2AX-S139A and treated with 10 μM aphidicolin for 24 h. Each bar indicates mean + standard error of at least three independent experiments with at least 100 cells counted per experiment. (D) Fluorescence microscopic analysis of a U-2 OS cell transiently transfected with myc-H2A and stained with an anti-myc-tag antibody. Nucleus stained with DAPI. Scale bar indicates 10 μm. (E) Quantification of apoptotic U-2 OS cells following transient overexpression of empty myc-tag vector (control) or myc-H2A for 24 h. Each bar indicates mean + standard error of at least three independent experiments with at least 100 cells counted per experiment.