There is also the possibility that the contribution of AP-1 signaling to EMT in the metastatic process in HNSCC could be relatively low compared to those for other malignancies, as the greater number of gene mutations existing in HNSCC cells, due to a history of tobacco and/or alcohol use, could play an important role in HNSCC metastasis [27]. This evidence concerns the gene FOS and head and neck squamous cell carcinoma.