More than 50% of colonic tumours have a mutant p53 gene (Baker et al, 1990), and a functional p53 protein has been shown to be important for the cellular response to a variety of proapoptotic stimuli, including chemotherapeutic agents commonly used in the treatment of colorectal cancer, such as 5FU and CPT-11 (Bunz et al, 1999; Arango et al, 2001; 2003; Magrini et al, 2002). The gene discussed is TP53; the disease is colonic neoplasm.