EGFR and colorectal carcinoma: PGE2 may also regulate EGF signaling via canonical WNT pathway based on the evidence that PGE2 activates WNT signaling via TCF4 transcription factors by stabilizing CTNNB1 (β-catenin) in CRC cells [80] and Apc deficiency is associated with increased Egfr activity in the intestinal enterocytes in vivo [65].