MMP9 and gastric cancer: With this 2-step strategy, we identified 21 differentially expressed proteins in at least one of the paired samples in the training set, including 19 upregulated (GRO, MMP-9, IL-8, MMP-8, TIMP-1, Acrp30, ICAM-1, NAP-2, Angiogenin, HGF, b-FGF, RANTES, ENA-78, uPAR, sTNF RII, TIMP-2, EGFR, MCP-1 and IL-1β) and 2 downregulated (MIP-1δ and IGFBP-2) proteins in GC tissues.