Within all MMPs, MMP-9 plays a regulatory role in angiogenesis not only through proteolytic activity, but also through other downstream angiogenesis factors; study revealed that MMP-9 participated in the angiogenesis of tumors by increasing the effectiveness of VEGF, an important angiogenesis inducer in malignant tumor, indicating that the MMP-9 is a part of the angiogenic regulation [48]. Here, MMP9 is linked to cancer.