DNA double strand breaks (DSBs) can be repaired by end joining pathways that do not utilize significant homology at the broken ends, or through homologous recombination (HR). When HR is used for repair, in eukaryotes it is promoted by the recombinase RAD51 (EC 3.1.22.4), which binds to 3’-tailed single strands at the end of DSBs in a helical fashion and promotes pairing with homologous DNA sequences as a prelude to strand invasion and repair of the DSBs[1]. Five subtypes of the RAD51 recombinase family are known (RAD51B, RAD51C, RAD51D, XRCC2 and XRCC3), which all act to transduce the DNA damage signal to effector kinases and to promote break repair. RAD51 resides as a small monomeric molecule which assembles into long helical polymers that wrap around the ssDNA tail at the break site. The resulting nucleoprotein filament catalyses pairing with and strand invasion into an intact homologous DNA molecule. Assembly of RAD51 monomers onto ssDNA is a relatively slow process and is facilitated by several mediator proteins. The tumor suppressor protein BRCA2 is the best-characterized loader of RAD51 monomers at DSBs[2]. Overexpression of RAD51 is found in human tumors, and its increase is related to p53 function.