Expression of MMP2 in lung cancer with N2-N3 (18/33, 54.5%) of lymph node metastasis was up-regulated compared with that in lung cancer with N0-N1 (2/23, 8.7%) (p < 0.001) (Table 2, Fig. 2e). This evidence concerns the gene MMP2 and metastatic malignant neoplasm in the lymph nodes.