 The found that when the "rad9" mutant was arrested in G2, irradiated to induce DNA damage, and left arrested in G2 by MBC for 4 hours, the cell was able to repair DNA and divide normally.This result suggested that Rad9 is not necessary to repair DNA.They concluded that "Rad9" is an important gene that is crucial to arrest the cell in G2 and ensures fidelity of chromosome transmission but is not necessary to repair DNA.