Video 2
Specific subregions of H2AX -/- MEFs photoactivated by UV laser microirradiation without DNA damage. H2AX -/- cells expressing H2B-PAGFP were photoactivated in the absence of Hoechst dye and followed over a 10-min time period. The pre-UV (arrow denotes zoomed circular region shown in the inset) and post-UV H2B-PAGFP images are shown in the left panel, and corresponding differential interference contrast images are shown in the right panel. Images were collected every 20 s and were not corrected for cell migration or changes in rotation.