RAD51 and glioblastoma: HOP2–MND1 forms a meiotic complex necessary for loading DMC1 and RAD51 onto single-stranded DNA (ssDNA).20, 34 HOP2 and MND1 are more highly expressed in GBM as compared with normal brain (Figures 1a and b) and expression increases with tumor grade (Figures 1c and d).