Real time-PCR and Western blotting were used to detect CXCR4 expression in MKN45 and HGC27 cells (Figure 2A, B); and reveal it upregulated significantly in them after infection with H. pylori 26695 for 24 hours (P < 0.01, respectively, Figure 2A, B). The gene discussed is CXCR4; the disease is infection.