RNA polymerase III appears to be essential for homologous recombinational repair of DNA double-strand breaks. RNA polymerase III catalyzes the formation of a transient RNA-DNA hybrid at double strand breaks, an essential intermediate step in homologous recombination mediated double-strand break repair. This step protects the 3’ overhanging DNA strand from degradation. After the transient RNA-DNA hybrid intermediate is formed, the RNA strand is replaced by the RAD51 protein, which then catalyzes the ssDNA invasion step of homologous recombination.