MMP9 and esophageal squamous cell carcinoma: To explore whether M2 macrophages promote the invasion, metastasis and angiogenesis of Kazakh ESCCs by mediating of MMP9, we investigated the relationship between the density of M2 macrophages, MVD and the expression of MMP9, and we found significant correlation between MMP9 expression and the density of M2 macrophages either in the ESCC tumor islets or tumor stroma.