MMP9 and ischemia: In particular, MMP‐2 and MMP‐9 are critical for the degradation of basement membrane type IV collagen, increased vascular leakage, and increased IFP.41 In the tumor tissue, the expression levels of MMP‐2 and MMP‐9 are elevated due to ischemia and hypoxia, and type IV collagen of the vascular basement membrane is degraded, resulting in destruction of the vascular structure.