There are two main theories for the mechanism by which serpin E2 enhances tumor cell metastatic ability: 1) formation of covalent complexes by binding to its target protein, which promotes the expression of MMPs, thus degrading the ECM and mediating tumor cell metastasis; and 2) promotion of angiogenesis in the TME, leading to tumor metastasis. This evidence concerns the gene SERPINE2 and neoplasm.