Although the structures of the BRCA1 and BRCA2 genes are very different, at least some functions are interrelated. The proteins made by both genes are essential for repairing damaged DNA. BRCA2 binds the single strand DNA and directly interacts with the recombinase RAD51 to stimulate and maintain strand invasion, a vital step of homologous recombination. The localization of RAD51 to the DNA double-strand break requires the formation of the BRCA1-PALB2-BRCA2 complex. PALB2 (Partner and localizer of BRCA2) can function synergistically with a BRCA2 chimera (termed piccolo, or piBRCA2) to further promote strand invasion. These breaks can be caused by natural and medical radiation or other environmental exposures, but also occur when chromosomes exchange genetic material during a special type of cell division that creates sperm and eggs (meiosis). Double strand breaks are also generated during repair of DNA cross links. By repairing DNA, these proteins play a role in maintaining the stability of the human genome and prevent dangerous gene rearrangements that can lead to hematologic and other cancers.