Figure 4. Expression of DDR proteins. (A) Protein levels of DDR factors were determined by Western Blotting (representative blots are shown in Supplementary Figure 5). Protein band intensities were quantified and normalized to loading controls. Normalized values for PBL derived from young female or male donors respectively were set to 100% for each blot. Columns, means of relative protein levels; bars, SEM from 1-11 donors per age group (Supplementary Table 1). (B) mRNA levels of KU70, BLM and ATM determined by RT-qPCR. Columns, mean 2-ΔCt values; bars, SD; female: n=3 (young), n=5 (old); male: n=3 (young), n=4 (old) (Supplementary Table 1).