RAD51 and glioblastoma: Moreover, clonogenic survival assay demonstrated that the sensitizer enhancement ratio (SER) of B02 treatment on cell survival was almost the same with the SER of B02 plus siCD81 (1.1343 ± 0.0252 vs. 1.1421 ± 0.0198 for U251R cells; 1.1321 ± 0.0155 vs. 1.1343 ± 0.0145 for T98G cells) (Figure 6C,D), suggesting that Rad51 was an indispensable effector of CD81-mediated radioresistance in GBM cells.