Chromosome breakage induced by the genotoxic agents mitomycin C and cytosine arabinoside is concentration and p53 dependent.

The p53 tumor suppressor protein plays an essential role in cellular integrity and inactivation of the TP53 gene by mutation is the most frequent alteration in human cancer. As loss of p53 function is associated with increased genetic instability, it is important in genotoxicity testing to explore the role of p53 competency. In vitro model systems for genotoxicity testing are sometimes prone to misleading positive results; some of this loss of predictivity may be caused by p53 inactivation in some cell models.