Helicobacter pylori lives in the stomach lumen adhering and specifically inter acting with gastric epithelial cells. H. pylori infection can cause a broad range of diseases. Although most infected individuals only develop a chronic inflammation of the stomach; some patients progress to chronic gastritis, duodenal ulceration, or, rarely, cancer. H: pylori. is able to send and to receive signals from the gastric epithelium, allowing host and bacteria to become linked in a dynamic equilibrium. Several studies have demonstrated that H. pylori infection induces morphological changes of gastric epithelial cells other than cell proliferation, increase of mitosis and mutations. It has also been demonstrated that H. pylori may predispose to cancer by altering gastric epithelial cell turnover actin specifically on transcription factors. Although H. pylori is able to induce several host responses, it specifically perturbs the delicate balance of those factors that usually help to maintain Cell. homeostasis. The study of mechanisms of interaction between the bacterium and gastric cells will surely help to prevent the increase and diffusion of malignancies all over the world. (C) 2004 Wiley-Liss, Inc.