TP53BP1 and cancer: Additionally, the co-localization of telomeric 53BP1 or γ-H2AX signals and telomeric FISH analysis revealed that telomere damage or dysfunction could not be rescued without telomerase in telomerase-positive cancer cell lines, including HeLa (Fig. 6b–f and Fig. S5E, F) and MCF-7 cells (Fig. S5G–I).