SNAI2 and head and neck squamous cell carcinoma: The involvement of TGF-β1 and IL-6 as EMT-inducers, in the regulation of the protein products of KLF4, Slug and VIM (Vimentin) were investigated in control and 1 ng/mL TGF-β1 or 50 ng/mL IL-6—treated conditions in HNSCC cell lines.