In line with this, it has been demonstrated that nicotine plays a critical role in the development of tobacco-induced cancers by increasing the expression of various CSC markers NANOG, OCT4, CD44, and BMI-1 and regulating CSC properties and tumorigenic potential in HNSCC models in vitro and in vivo [35]. This evidence concerns the gene POU5F1 and head and neck squamous cell carcinoma.