CHEK2 functions downstream of ATM (ataxia telangiectasia-mutated protein) in response to DNA damage (Chaturvedi et al, 1999) to phosphorylate TP53 (Chehab et al, 2000) and BRCA1 (Lee et al, 2000), therefore regulating the tumour suppressor functions of these proteins. The gene discussed is CHEK2; the disease is neoplasm.