MMP2 and neoplasm: Previous studies have shown that MMP2 and MMP9 are highly expressed in most tumor tissues, whereas normal tissues/cells and adjacent normal tissues surrounding tumors exhibited negligible expression.[15] Immunohistochemical analysis revealed that the positive areas of MMP2 and MMP9 staining were relatively higher in LLC tissues, which provides a preferable environment for N@VP aggregation and VP release (Figure S8a,b, Supporting Information).