The anticancer effects of melatonin are mediated not only by the Wnt/β-catenin pathway but also through a complex network of signalling pathways, mainly involving the phosphatidylinositol 3-kinase/AKT/mechanistic target of rapamycin (PI3K/AKT/mTOR), NF-κB, ERK, and cyclooxygenase-2/prostaglandin E2 (COX-2/PGE2) signalling pathways, responsible for the anti-proliferative and pro-apoptotic effects on cancer cells [114,115], and c-Jun N-terminal kinase (JNK), Akt-MAPKs, and NF-κB pathways, responsible for anti-metastatic effects [116,117]. The gene discussed is PTGS2; the disease is cancer.