簡要描述：DNA damage or incomplete replication of DNA results in the inhibition of cell cycle progression at the G1 to S or the G2 to M phase transition by conserved regulatory mechanisms known as cell cycle checkpoints. Checkpoint proteins include Rad17, which is involved in regulating cell cycle progression at the G1 checkpoint as well as Chk1, Chk2, Rad1, Rad9 and Hus1, which are involved in regulating cell cycle arrest at the G2 checkpoint. In response to DNA damage, ATM and ATR kinases are importa