APC and malignant colon neoplasm: Based upon the data presented here and in keeping with the ‘just right’ model for colorectal carcinogenesis, which states that specific APC genotypes are selected during tumour formation on the basis of the specific level of residual β-catenin downregulating activity that is retained, additional signals are likely required for the development of human colon cancer (Albuquerque et al, 2002).