RAD51 foci in parental and SUMO4Tcl1.11 cells treated with NTC or SUMO4 siRNAs expressing Abraxas (SA phosphorylation/BRCA1 interaction mutant) or BRCC36 (HQ catalytic inactive mutant) expression, exposed to IR (4 Gy), fixed 2 h later. N> 100 per condition for a total of three experiments. Bars are mean ± SEM. Statistical analysis: two-tailed t test.
