Similarly, it has been found that increased MMP-9 levels and decreased levels of tissue inhibitors of metalloproteinases (TIMP-1 and TIMP-2) stimulate tumor progression and metastasis in esophageal cancer, whereas TIMP-2 also shows decreased levels in PCs.[25,26] Whether the increase in MMP-9 levels and decrease in TIMP-2 levels promote tumorous malignant transformation in PCs requires further research. This evidence concerns the gene TIMP1 and neoplasm.