Figure 9. An interaction between 53BP1-H4K20me2/me3. (A) Immunoprecipitation (IP) experiments showed an interaction between H3K9me3 and 53BP1 or H4K20me2 and 53BP1 or H4K20me3 and the 53BP1 protein. HP1β protein did not interact with the 53BP1 protein. (B) Quantification of IP fragments from panel (A) studied in non-irradiated and γ-irradiated Suv39h1/h2 wt and Suv39h1/h2 dn cells. Asterisks (*) indicate statistical significance at P≤0.05.