CHEK1 and cancer: Other critical components of the DDR, including ataxia telangiectasia and Rad3-related (ATR), ataxia telangiectasia mutated (ATM), DNA-dependent protein kinase (DNA-PK), Checkpoint kinase 1 (CHK1), Checkpoint kinase 2 (CHK2) and Wee1 kinase (WEE1), are also promising as targets for fighting cancer [6,7].