APC and neoplasm: Impaired degradation of β-catenin in tumours has been reported to be caused by inactivating mutations in APC, AXIN1, AXIN2 or β-TrCP or oncogenic mutations in β-catenin exon 3 (Kinzler and Vogelstein, 1996; Bienz and Clevers, 2000; Liu et al, 2000; Polakis, 2000; Satoh et al, 2000b; Gerstein et al, 2002; Hajra and Fearon, 2002; Taniguchi et al, 2002; Yokota et al, 2002).