Background of the antigen
DNA damage results in the arrest of cell cycle progression, allowing the damaged DNA to be repaired prior to replication. Checkpoints exist at several cell cycle phase transitions to maintain this genetic integrity. Rad9, Rad17, Rad24 and Mec3 are involved in activating the G1 and G2 checkpoints (1–4). Pol2 (also known as Dun2), encoding the catalytic subunit of DNA polymerase epsilon, plays a role in activating the S phase checkpoint (5). The protein kinase Rad53 (also designated Spk1, Mec2 or Sad1) is essential for both G2 and S phase arrest. Activation of Rad53 is regulated by Mec1 (also known as Esr1 and Sad3), a homolog of the human ATM protein (6). Pds1 and Mad2 both regulate checkpoints associated with incomplete spindle replication (7,8). Dun1, another protein kinase, plays a role in transducing the DNA damage signal (9).
