Among matrix metalloproteinases (MMPs), thesecreted gelatinases MMP-2 and MMP-9 are responsible for the degradation of gelatinin the extracellular matrix and type IV collagen in the basement membrane; and thisdegradation event is crucial for the migration from the origin and the invasion intothe bone in HNSCC. This evidence concerns the gene MMP9 and head and neck squamous cell carcinoma.