S100A4 and head and neck squamous cell carcinoma: To further investigate how S100A4 is involved in stemness property, we established stable HNSCC cell lines expressing different dysfunctional S100A4, of which the calcium-binding site on N-terminal (NM) or C-terminal (CM) were mutated because loss of the calcium-binding activity of S100A4 abrogates its physiological function and interaction to the target proteins [24, 25].