compared the protein profiles between three prostate cancer radiation therapy-resistant cell lines (PC3-RR, DU145-RR, and LNCaP-RR) and their cognate radiation sensitive cell lines, the result revealed five proteins were significantly altered: NME/NM23 Nucleoside Diphosphate Kinase 1 (NME1), Heat Shock Protein Family A Member 8 (HSPA8), Apurinic/Apyrimidinic Endodeoxyribonuclease 1 (APEX1), and Ras-related protein Rab-11A (RAB11A); APEX1 was an DNA repair enzyme, knockout of APEX1 significantly enhanced radiosensitivity of prostate cancer cells (85). This evidence concerns the gene LIG4 and Familial prostate cancer.