BRC4wt, an acetylated peptide originating from the BRC4 repeat within human BRCA2 (1521-1536), acts as an inhibitor of the BRCA2 and RAD51 protein-protein interaction. When linked to the cationic cell-penetrating peptide (Arg)9, it effectively shortens DNA replication tract lengths and diminishes the frequency of homologous repair of camptothecin-induced DNA damage in vitro. Additionally, BRC4wt enhances the efficacy of the poly(ADP-ribose) polymerase (PARP) inhibitor olaparib in inducing cell death in HeLa human cervical cancer and U2OS human osteosarcoma cells, albeit it does not affect non-cancerous hTERT RPE-1, MRC-5, or MCF-10A cells.