Ku70 overexpression ameliorates mutant Htt–induced activation of H2AX in mouse striatal neurons in vivo. Immunohistochemistry of striatal neurons of R6/2 mice or of R6/2 × Ku70 double-transgenic mice at 4 wk. Anti-NeuN and -γH2AX antibodies were used. Bars, 10 µm. (bottom) Quantitative analysis of >100 neurons from four nontransgenic littermates, four R6/2, and four double-transgenic mice is shown. The mean values of four mice were compared among groups. The signals of γH2AX in the nucleoplasm were reduced in comparison with R6/2. The γH2AX signals were focused to the nucleoli in double-transgenic mice. *, P < 0.01 by Student’s t test (n = 4). Error bars indicate SEM.