The H pylori protein CagA might function as a bacterium-derived oncoprotein in the carcinogenesis of gastric MALT lymphoma. (A) Translocation of CagA (EGFP) into BJAB (Epstein-Barr virus-negative Burkitt lymphoma) cells is revealed by immunohistochemical staining of cell surface IgM (red) and confocal microscopy. (B) H pylori–derived CagA can be translocated into B lymphocytes. Intracellular CagA coimmunoprecipitates with SHP-2, suggesting the involvement of CagA in the regulation of intracellular signaling pathways. Modified with permission from Lin et al.⁴⁹