In human postmortem AD brains, western blotting with anti-pSer77/78 antibody revealed the increase of PKCα-type phosphorylation of Ku70 in comparison to non-neurological disease controls (Fig. 5d, left panels) and immunohistochemistry with anti-pSer77/78 antibody suggested that the increase of pSer77/78 Ku70 occurred in cortical neurons, and that pSer77/78 Ku70 together with total Ku70 shifted from the nucleus to the cytoplasm (Fig. 5e). Here, XRCC6 is linked to Alzheimer disease.