Candidate DNA repair genes and somatic instability. (A) Gene expression levels (Msh2, Msh3, Cbp, Ogg1) and measured instability indices of 16 training tissues were plotted. Among multiple probes representing the same gene, the probe with the highest expression level in striatum was selected. Expression levels showed insignificant correlations for Msh3, Cbp and Ogg1 and a negative correlation for Msh2 with measured instability indices. (B) Protein levels of Msh2 were measured in 2 unstable (striatum and liver) and 2 stable tissues (cerebellum and spleen) from HdhQ 111/+and corresponding control mice (n = 3 mice per genotype, 2 months). Whole cell protein extracts (70 μg) were resolved by SDS-PAGE (6%) and western blots were performed for Msh2 (Santa Cruz Biotechnology) and Tubulin (Cell Signaling). ST, striatum; CB, cerebellum; LV, liver; SP, spleen. (C) Microarray expression levels of Msh3 (Affymetrix probe ID, 1430643_at and 1446511_at) in FACS-purified astrocytes and neurons were obtained from the GSE9566 data set. Msh3 expression level in astrocytes was not significantly different from that in neurons. Data bar represents mean of log2 expression levels ± SD (n = 8-10).