DNA-binding protein that accumulates at DNA double-strand breaks (DSBs) following DNA damage and promotes DNA resection and homologous recombination. Serves as a sensor of DNA damage: binds DNA with a strong preference for DNA substrates that mimic structures generated at stalled replication forks, and anchors RBBP8/CtIP to DSB sites to promote DNA end resection and ensuing homologous recombination repair. Inhibits non-homologous end joining (NHEJ). Required for the dynamic movement of AURKA at the centrosomes and spindle apparatus during the cell cycle. Interacts (via C-terminus) with AURKA (via C-terminus). Interacts (via N-terminus) with NIN; this interaction blocks NIN phosphorylation by both AURKA and GSK3B. Identified in a complex with NIN and AURKA. Interacts with RBBP8/CtIP. Accumulates at sites of DNA damage by binding to DNA substrates that mimick structures generated at stalled replication forks. Localizes to the centrosome in interphase and to the spindle pole in metaphase. Belongs to the AUNIP family.