Moreover, 53BP1 foci, which represent sites of double strand DNA breaks [54], were markedly increased in the cancer cells treated by the combination of ATL and olaparib for 12 h and both NAC and the DNA replication inhibitor aphidicolin dramatically reduced the number of 53BP1 positive cells (Fig. 5e and Fig. S7B). Here, TP53BP1 is linked to cancer.