APC and carcinoma: Notably, both Apc1638N/+ adenomas and Apc1638N/+/KRASV12G carcinomas share the same “β-catenin paradox” observed in human colon cancers in that, upon IHC analysis, only a minority of tumour cells show nuclear β-catenin accumulation notwithstanding that the majority, if not all, share the two-hits at the Apc locus [12], [14] (Figure 2a).