This shows crosslink-inducing agents used in chemotherapy. Environmental influences such as ionizing radiation, intense heat or various chemical substances damage the DNA constantly. Only thanks to efficient repair systems can mutations – changes in the DNA – largely be prevented. DNA crosslinks that covalently link both strands of the DNA double helix are among the most dangerous DNA lesions. Crosslinks block DNA replication and can thus cause cell death. Moreover, their faulty repair can trigger the development of tumors. Crosslink repair is highly complex and only vaguely understood today. A team of cancer researchers headed by Alessandro Sartori from the University of Zurich now reveals interesting details as to how cells recognize crosslink damage. In their study recently published in Cell Reports, the scientists demonstrate that the interplay between two specific proteins is crucial for the flawless repair of crosslink damage.