MMP9 and malignant colon neoplasm: Zeng et al. reported that the expression of MMP2, MMP9, and VEGF was significantly reduced after treatment with an HIF-1α inhibitor, and the VM ability of tumor cells was also significantly limited, suggesting that the HIF-1α/MMP2 or HIF-1α/MMP9 signaling pathway is involved in the proliferation and metastasis of colon cancer, fully demonstrating that HIF-1α exerts a biological regulatory function on colon cancer cells through MMP2 or MMP9 [77].