TGFB1 and head and neck squamous cell carcinoma: In addition, various in vitro studies demonstrated that EMT in HNSCC cells can be induced by CAF-derived molecules, such as SDF-1 via activation of the PI3K-Akt/PKB signaling pathway [358], TGF-β1 via the TGF-β/Smad signaling pathway [359], endothelin-1 [360] and CCL-7 [17].