XRCC6 and cancer: For example, in cancersoverexpressing SIRT3, like head and neck squamous cell carcinoma (HNSCC),SIRT3 keeps the ROS species at an adequate rather low level, resultingin a malignant phenotype.76 In HeLa cells,SIRT3 removes acetyl groups from Ku70, leading to increased Ku70-Baxinteractions and subsequently facilitating the movement of Bax tothe mitochondria, thus leading to cancer cell survival through protectionfrom genotoxic and oxidative stress.77