S100A8 and infection: The second point is that although between 60-70% of H. pylori strains are Cag PAI+, the high rate of mutation and infection with multiple strains may allow for not only Cag PAI+, but also CagA-negative strains to promote tumor cell motility.[41] Thus, a greater population of H. pylori strains in the stomach may play a role in gastric cancer progression to metastatic disease than previously suggested.