Certain critical or unstable regions are kept in check, so if you get mutation there cell undergoes apoptosis. This is for cancer avoidance though. There are a

Certain critical or unstable regions are kept in check, so if you get mutation there cell undergoes apoptosis. This is for cancer avoidance though. There are also a host of proteins that check for DNA breaks, damage from UV or other carcinogens and just generally keep an eye on things.