The RAD51 protein is a crucial factor in homologous recombination repair (HR), and its family includes RAD51 itself and homologs such as RAD51B, RAD51C, RAD51D, XRCC2, and XRCC3. These proteins are localized in the cell nucleus, forming complexes that mediate the repair of DNA double-strand breaks. RAD51 maintains genome stability by facilitating pairing and exchange between homologous DNA sequences. Its expression is strictly regulated throughout the cell cycle to ensure the proper progression of DNA replication and repair processes. Specific gene mutations are closely associated with cancer, indicating that RAD51 and its family members play a crucial role in maintaining normal cellular function.