Cell cycle checkpoint signaling through the ATR and ATM kinases

Ataxia-telangiectasia mutated (ATM) plays a key role in regulating the cellular response to ionizing radiation. Here,we highlight some of the new developments in the fields in our understanding of the mechanism of activation of ATM and ATR and their signaling pathways, address some of the prominent,unanswered questions related to ATM and ATR structure and function. The scope of this article is to provide a brief overview of the recent literature on this subject and to raise questions that could be addressed in future studies.