Figure 2.

Graphical representation of the ATM-CHK2 and ATR-CHK1 signaling cascades

In response to DSBs or SSBs, the kinases ATM and ATR becomes activated and, collaborating with the transducer kinases CHK2 and CHK1 promote the phosphorylation of a plethora of targets. Phosphorylation of these substrates finally induces the appropriate cellular response to the lesions, that could be the induction of senescence or apoptosis, the activation of cell cycle checkpoints, and the promotion of DNA repair.