XRCC6 and nasopharyngeal carcinoma: Moreover, western blotting unveiled that circCDYL2 promoted the expression levels of RAD51 protein in nasopharyngeal carcinoma cells (Fig. 3D), while it did not influence the expression of BRCA1, RPA1, or Ku70, a key protein within the NHEJ pathway (Supplemental Fig. 3C).