Using the liver as a model system, we have interrogated non-tumour roles for p53 activity during both the acute and chronic responses to the liver toxin and carcinogen CCl4. We identified p53-mediated redox control and induction of CYP2A5/CYP2A6 as important features of the hepatic p53 response both in vivo and in human liver cancer cell lines in vitro. The gene discussed is TP53; the disease is neoplasm.