TP53 and neoplasm: CHK2 is regarded as a tumour suppressor due to its role in apoptosis regulation with or without the involvement of ATM; upon phosphorylation, activated CHK2 phosphorylates the tumour suppressor gene P53 and multiple CDC25 molecules that negatively regulate kinase activation in a cyclin-dependent manner, which may provide insight into the potential mechanism of ITGB1-mediated radioresistance 61.