Adenomatous polyposis coli (APC) is a protein that plays a critical role in several cellular processes. APC is a tumor suppressor, regulates cell division, helps ensure that the number of chromosomes in a cell is correct following cell division and associates with other proteins involved in cell attachment and signaling. APC regulates ß-catenin levels through Wnt-signaling and is involved in actin cytoskeletal integrity, cell-cell adhesion and cell migration. Defects in this gene cause familial adenomatous polyposis (FAP), an autosomal dominant pre-malignant disease that usually progresses to malignancy. Disease-associated mutations tend to be clustered in a small region designated the mutation cluster region (MCR) and result in a truncated protein product.