MMP9 and gastric cancer: Especially, previous studies uncovered that the serum expression level of CXCL13 in GC patients with lymph node metastasis was significantly higher than that in those without lymph node metastasis115 and overexpression of CXCR4 in primary gastric cancers was certified as an independent risk factor for lymph node metastasis,116 while HSP90AA1 was correlated with MMP9 to promote cell invasion and lymph node metastasis in GC patients.119