DNA-PK (DNA-dependent protein kinase) is a crucial cellular repair enzyme composed of three main components: the catalytic subunit DNA-PKcs (encoded by the PRKDC gene) and the two DNA binding subunits Ku70/Ku80. It primarily localizes in the cell nucleus, participating in the non-homologous end joining (NHEJ) pathway, responsible for repairing DNA double-strand breaks. DNA-PK is expressed in various cell types, particularly in actively dividing cells. Mutations or dysregulation in gene expression can lead to repair defects, associated with various genetic diseases and cancer development. The activity and expression levels of DNA-PK are critical factors in cellular responses to DNA damage and the maintenance of genomic stability.