Thus, we explored the expression profiles, activation ratio, and localization of MMP-9 activity in tissue sections of papillary thyroid carcinomas and correlated the findings with clinicopathological prognostic factors with the aim of determining whether MMP-9 may be a useful adjunctive tool for predicting unfavorable biological behavior of PTC. This evidence concerns the gene MMP9 and thyroid gland papillary carcinoma.