In Nature this week, investigators in Tokyo and Toronto report that "OTUB1, a deubiquitinating enzyme, is an inhibitor of DSB-induced chromatin ubiquitination." The authors write that they were surprised to find that OTUB1 binds and inhibits UBC13, consequently suppressing RNF168-dependent poly-ubiquitination "independently of its catalytic activity." The team suggests that "pharmacological targeting of the OTUB1–UBC13 interaction might enhance the DNA damage response."