Fig. S1. (A) Generation of isogenic stable lines. Stable lines were generated in BS/A-15 cells by stable transfection of shRNA against RAD54. The levels of BLM, RAD54 and hsp90 were detected by western blots. (B) Determination of SCE in cells depleted with BLM and/or RAD54. SCE per cell was determined in the isogenic cell lines A-15, A-15 shRNA-RAD54, BS, BS shRNA-RAD54. Two independent clones for A-15 shRNA-RAD54 and two independent masses for BS shRNA-RAD54 were used.

Fig. S2. Levels of RAD51 in A-15 and BS cells. (Left) Nuclear extracts from A-15 and BS cells were probed with antibody against GFP. (Right) Parallel blots were probed for RAD51 and hsp90.

Fig. S3. (A) Expression of dominant-negative RAD51 decreases HR in NHFs. (Left) Increasing amounts of dominant-negative RAD51 (SMRAD51) were transfected into NHF. The levels of expression of SMRAD51 were verified by western analysis with antibodies raised against RAD51. Expression of BLM, RAD54 and hsp90 were verified by respective antibodies. (Right) Expression of SMRAD51 led to a decrease in HR as measured by host cell reactivation assay. (B) RAD54 and BLM colocalize even in absence of functional RAD51. IF analysis was carried out with antibodies against BLM and RAD54 in NHFs expressing SMRAD51.