Therefore, control of β-catenin and/or control of its downstream target gene expression represents an ideal target for cancer therapeutics and chemoprevention [11], [12], [13].Van de Wetering et al. reported that knockdown of β-catenin by small interfering RNAs (siRNAs) or knockdown of TCF-4 by dominant negative TCF-4 (dnTCF) efficiently inhibited the activity of the TCF-reporter TOPFlash and induced cell cycle arrest and growth arrest in Ls174T colon cancer cells [14], [15]. Here, TCF4 is linked to cancer.