To assess if these HNSCC cell lines also express both functional uPA and MMP cell surface proteolytic activity, we next exposed the five HNSCC cell lines to the same concentration of FP59 in combination with increasing concentrations of intercomplementing PA (PA-U2-R200A + PA-L1-I210A) (Figure 1B). This evidence concerns the gene PLAU and head and neck squamous cell carcinoma.