Radiobiology 2016

Summary of Checkpoints

• Checkpoints are activated by inhibiting CDK ’ s • Checkpoints are often disrupted in cancer • 4 Checkpoints are activated by IR – G1 (ATM-p53), S (ATM), G2 early (ATM/ATR), G2 late (ATR) • Loss of checkpoints affects tumor proliferation after IR – Can affect cell cycle R edistribution, response to multiple fractions