Notes: Mirin is an inhibitor of the Mre11/Rad50/Nbs1 (MRN) complex, which functions as a DNA damage sensor and activates the DNA repair enzyme ataxia-telangiectasia mutated kinase (ATM).{16934} It inhibits phosphorylation of H2AX induced by DNA containing dsDNA breaks (DSBs), indicating decreased ATM activation, with an IC50 value of 66 µM in X. laevis cell-free extracts. Mirin (100 µM) also inhibits the exonuclease activity of Mre11 in a cell-free assay. It induces cell cycle arrest at the G2 phase in TOSA4 cells and inhibits homology-dependent repair in HEK293 cells in a concentration-dependent manner. Nanoparticle-encapsulated mirin (50 mg/kg) reduces tumor growth in an LA-N-5 mouse xenograft model.{60776}