The Ku70/80 Colorimetric Cell-Based ELISA provides a lysate-free, convenient, and high-throughput approach for sensitive detection of Ku70/80 protein expression profile in cells. The kit can be used for measuring the relative amounts of Ku70/80 in cultured cells as well as screening for the effects that various treatments, inhibitors (ie siRNA or chemicals), or activators have on Ku70/80.