**2. APC gene in colorectal cancer**

Colorectal cancer (CRC) is the final outcome of a multi-step process that, in most cases, proceeds down the adenoma–carcinoma sequence pathway (2).

The tumor suppressor gene mutation involving the *Adenomatous Polyposis Coli* (APC) gene is present in 80% of sporadic CRCs and 100% of cases of *Familial Adenomatous Polyposis* (FAP). In humans, the APC mutation provides the genetic background to the onset of the tumor process, making intestinal cells susceptible to tumor progression and promotion through the accumulation of further mutations as a result of epigenetic phenomena largely influenced by environmental factors (3).

FAP offers an ideal model for the study of CRC since in these patients "normal" mucosa coexists with low and high-grade dysplastic lesions as well adenocarcinoma, i.e. all the stages of the carcinogenetic process. For this reason the modifications occurring during the carcinogenetic process are easily comparable and free from individual variations (4).
