PRKDC and breast carcinoma: Our continued characterization of uncapped (as opposed to shortened) dysfunctional telomeres in cells deficient for the catalytic subunit of DNA-PK (DNA-PKcs) provided the first indication that such uncapped telomeres are inappropriately detected and processed as DSBs [4], as well as evidence of their contribution to genomic instability and carcinogenesis, specifically murine mammary carcinoma following exposure to ionizing radiation (IR) [5].