PRKDC and cancer: Under hypoxic conditions, additional DNA repair pathways can be activated.16,376–379 HIF-1α stimulates DNA-dependent protein kinase (DNA-PK) expression and repairs DNA DSB caused by ionizing radiation.380 Radiation upregulates HIF-1 expression and enhances its activity in cancer cells.381 Elevated HIF-1α levels confer radioresistance via various pro-cancer mechanisms.