Complex immunoprecipitation (Co-IP) studies within mouse embryonic stem cells (mESCs) ([55] and later in CRC cell lines [13, 56]) revealed a direct interaction between BCL3 and β-catenin; various BCL3 mutant constructs were used to identify a region immediately 5′ of the ANK-repeat region of BCL3 (between amino acids 31 and 125) which were required for β-catenin complex formation [56]. The gene discussed is BCL3; the disease is colorectal carcinoma.