Defects in the regulation of beta-catenin in colorectal cancer.

The molecular events that contribute to the progression of colon cancer are beginning to unravel. An initiating and probably obligatory event is the oncogenic activation of beta-catenin. This can come about by the loss of its negative regulator the adenomatous polyposis coli (APC) protein, or by mutations in the beta-catenin gene that result in a more stable protein product. The interaction between APC and beta-catenin, and additional proteins that affect assembly and signaling along this pathway, are discussed.