Figure 3. H3K27 is not methylated upon laser induced DNA damage. (A) U2OS cells were laser micro-irradiated and then fixed with 4% paraformaldehyde 5 min after laser induced DNA damage. Cells were then co-immunostained with H3K27me3 and γ-H2AX antibodies. (B) U2OS cells were exposed to 2 Gy and then left to recover for 30 min. Cells were then fixed with 4% PFA and co-immunostained with H3K27me3 and γ-H2AX antibodies. (C) U2OS cells were either not treated or treated with 8 Gy and left to recover for 30 min before harvesting. Nuclei were extracted, sonicated, and run on an 18% polyacrilamide gel. The western blots were stained with H3K27me3 and γ- H2AX to show the induction upon ionizing radiation.