TACSTD2 and thyroid cancer: Trop2 seems to be critical in regulating MMP2 expression in our study because our data revealed upregulation of MMP2 mRNA level and activation of MMP2 promoter reporter in Trop2-overexpressing thyroid cancer cells, as well as down-regulation of MMP2 mRNA and inactivation of MMP2 promoter reporter in Trop2 knocked down thyroid cancer cells.