Reaching out for the other end with p53-binding protein 1

Correct joining of broken chromosomes is indispensable to prevent cell death, ageing and cancer. Two recent papers highlight the importance of p53-binding protein 1 (53BP1) in connecting distant sites in T-cell receptor loci and dysfunctional telomeres. These studies refine our understanding of the specific subset of DNA double-strand breaks that require the accessory end-joining factor 53BP1.