RAD51 and breast carcinoma: To this end we tested the effect of small molecule inhibitors of PAK and PARP, alone and together, on Rad51 foci formation in breast cancer cells with amplification or overexpression of PAK1. These compounds included PF-3758309 and Rucaparib, which is a potent inhibitor of PARP-1 and PARP-2 [22].