Chromosome structure is shaped by the protein complexes that contain members of the Structural Maintenance of Chromosome (SMC) family. One of these protein complexes called cohesin tethers replicated chromosomes to mediate sister chromatid cohesion.Sister chromatid cohesion was thought to play only an indirect role in DNA damage repair. In this book, we report our detailed analysis of cohesin in response to a particular type of DNA damage called DNA double-strand breaks (DSBs).There are three major conclusions from this work. First, DSBs induce de novo recruitment of cohesins to the broken...