NFATC1 and gastric mucosa-associated lymphoid tissue lymphoma: CagA and NFATc1 colocalized in the lymphoma cells of patients with HPE-responsive gastric MALT lymphoma, and the combined presence of CagA and nuclear localization of NFATc1 increased the PPV (90.5%) and specificity (87.5%) for HPE responsiveness compared with CagA expression alone.