Their results demonstrated that RGD-NPVs@MNPs/DOX evaded immune clearance and achieved chemical photothermal elimination of drug-resistant breast tumour cells and the tumour vascular system, resulting in various effects, including reversing multidrug resistance to effectively kill drug-resistant cancer cells; eliminating the tumour vascular system to block the supply of nutrients to the tumour and metastasis; and permanently inhibiting the expression of VEGF, MMP-2, and MMP-9. This evidence concerns the gene MMP9 and neoplasm.