• Role in the regulation of epithelial–mesenchymal transition through increasing expression of N-cadherin and Slug [77]. • Observed in metastatic lymph nodes and recurrent tumors from OSCC patients [10]. • Correlated with poor survival and considered as an independent prognostic marker of HNSCC progression [58, 65]. This evidence concerns the gene SNAI2 and head and neck squamous cell carcinoma.