TCF4 and colorectal carcinoma: Among other aberrantly induced genes downstream of the nuclear β-catenin/TCF4 complex, some are direct OPN regulators that may participate in a positive regulation loop such as c-MYC, a major oncogene known to drive colorectal carcinogenesis [46,47]; the lymphoid enhancer-binding factor-1 (LEF1), which have prognostic value in CRC with respect to recurrence and metastasis [48]; and c-Jun, which is able to form by homo-dimers and hetero-dimers with c-FOS (called the Activator protein-1, AP-1), which is also implicated in CRC [49].