TP53BP1 and cancer: Our previous experiments based on IF analysis using FFPE tissues also found that the number of 53BP1 nuclear foci increased in irradiated rat thyroid glands in a dose-dependent manner, and frequent co-localization of 53BP1 and γH2AX nuclear foci occurred in human FTCs, suggesting the endogenous activation of DDR pathways in cancer cells as a hallmark of genomic instability [16,17].