Mass spectrometry analysis of protein expression from tissues obtained from patients with metastatic gastric cancer and tumor adjacent normal tissue revealed that whereas five proteins (PCBP1, DSP, FZD7, ITGA5, and MMP2) were downregulated at least 3 folds (log2), four proteins (IGFBP4, KRT19, NODAL, and PRP4A1) were upregulated at least 3 folds (log2) in metastatic tumor tissue specimens compared to control tissue specimens. Here, MMP2 is linked to gastric cancer.