Immunohistochemical staining of MMP1 revealed a reduced positive signal in tumor xenografts and pulmonary metastatic lesions generated from AEG-1-knockdown HNSCC cells, as compared to the cytosolic and juxtacellular staining of MMP1 observed in lesions arising from control cells (Figure 4D). Here, MMP1 is linked to head and neck squamous cell carcinoma.