p53 is a tumour suppressor that is found mutated or functionally inactivated in more than half of all human cancers. p53 function is activated by DNA damage, hypoxia, expression of certain oncogenes, and many cytotoxic stimuli. p53 is a transcription factor that regulates expression of target genes which promote apoptotic cell death, cell cycle arrest.. cellular senescence, and some other processes. In this review we summarise current knowledge of p53 target genes implicated in apoptosis signalling. © 2005 Elsevier Inc. All rights reserved.