Figure 2.

Proposed mechanism for life/death decision making in genetically compromised cells. In healthy cells, arising DNA strand breaks are quickly repaired and do not accumulate. Correspondingly, the amount of Sp1 and DNA repair proteins only moderately fluctuates around basal levels. However, when the amount of DNA strand breaks exceeds the DNA repair capacity of the cell (point of no return), hyperactivation of ATM leads to Sp1 degradation and consequently to DNA repair downregulation, resulting in activation of cell death mechanisms (point of cell death).