XRCC5 and lip and oral cavity carcinoma: Liquid chromatography mass spectrometry analysis of immunoprecipitates, obtained from oral cancer cell lines SCC4 and MDA1986, demonstrated interactions with X-ray repair cross-complementing protein 5 and 6 (XRCC5 and 6 also known as Ku70 and Ku80) that bind broken DNA ends and mediate repair through NHEJ (Figure 1) [124,125].