SNAI1 and head and neck squamous cell carcinoma: Various teams have reported that EMT expression (i.e., Snail, Slug, Twist) alters kinetics in pre-clinical HNSCC in vitro migration-invasion studies [32–36] and retrospective patient studies have demonstrated an association of Snail and Slug expression with regional and/or distant cancer progression and chemoradiotherapy resistance [37–39].