Immunofluorescent Analysis of HP1γ and γH2AX

The corresponding cells were fixed in 4% formaldehyde for 10 min, then samples were treated in 0.5% (V/V) Triton X-100 for 15 min and blocked with 5% BSA for 30 min at 37 °C. After incubated with anti-HP1γ antibody (1:100) (Cell Signaling Technology, #2619, Danvers, MA, USA) and anti-γH2AX antibody (1:100) (millipore, 05-636, Darmstadt, Germany) overnight at 4 °C, samples were incubated with Alexa Fluor® 555 donkey anti-rabbit IgG (H + L) or Alexa Fluor® 555 donkey anti-rabbit IgG (H + L) (1:2000) for 60 min at room temperature and nucleus counterstaining with DAPI. Imaging was obtained by the Olympus FV1000 IX81-SIM Confocal Microscope (Olympus, Tokyo, Japan).