RAD51 and glioblastoma: This was further reinforced by a significant increase in the number of γH2AX-foci within the nucleus of glioblastoma cells, an indicator of DNA double-stranded breaks (Fig. 2G, p < 0.0001) and a concurrent reduction in the mean nuclear intensity of DNA-repair marker, RAD51 (Fig. 2H, p = 0.0002).