Damage to DNA is a constant threat to cellular life, and so it is constantly monitored and detected by a family of enzymes called RNA polymerases, resulting in subsequent repair to maintain genome integrity. In a paper published this week in the journal PNAS, researchers at University of California San Diego School of Medicine, with colleagues in Spain and Finland, describe for the first time how one type of RNA polymerase gets stalled by DNA lesions caused by exposure to ultraviolet (UV) light.