TNF and lip and oral cavity carcinoma: Syncytin-1 is an important fusogen that mediates cell–cell fusion [1], and it was upregulated through the Wnt/β-catenin pathway; thus, we concluded that TNF-α promoted fusion between oral cancer cells and vascular endothelial cells via the Wnt/β-catenin-dependent upregulation of syncytin-1 [88].