Using human CRC cells harboring different Wnt/β-catenin pathway mutations in APC/KRAS or β-catenin/KRAS genes, and both genetic and pharmacological knockdown approaches, we show that oncogenic β-catenin signaling negatively regulates the expression of NHERF1 (Na+/H+ exchanger 3 regulating factor 1), a PDZ-adaptor protein that is usually lost or downregulated in early dysplastic adenomas to exacerbate nuclear β-catenin activity. The gene discussed is NHERF1; the disease is colorectal carcinoma.