3T3 cells, 5min after the induction of DNA damage by microirradiation with a 405 laser. Cells were immunostained with antibody against H3K9me3 (green), a post-translational histone modification enriched at the pericentric heterochromatin domains. DNA damage sites (sites of irradiation) were visualized indirectly by H2AX (red) staining, DNA is stained with Hoescht 33258 (blue). This image is part of the original data set contributing to Baldeyron et al. (2011) HP1α recruitment to DNA damage by p150CAF-1 promotes homologous recombination repair J. Cell Biol. 193: 81-95.