Tokyo Metropolitan University Aug 10 2025 Researchers from Tokyo Metropolitan University have discovered a new pathway by which cells counteract the action of alovudine, an important antiviral and anticancer drug. The protein flap endonuclease-1 (Fen1) was found to improve cell tolerance by counteracting the toxic accumulation of another protein, 53BP1. A renewed spotlight on the underappreciated role of Fen1 promises not only new cancer treatments, but a way to gauge the efficacy of existing