Cox-2 dependent expression of ZO1 and Ornithine decarboxylase in MKN28 cells dependent in H. pylori infection. A. Expression of zona occludens-1 (ZO1) was determined by western blot at 6 h post infection in MKN28 cells with either H. pylori wild type P12 or the isogenic mutants missing the entire cag PAI (PAI), or VacA (VacA). ZO1 was up regulated after infection, independent of CagA PAI or VacA (upper), whereas the expression was decreased in cells treated with NS398 (lower). B. Expression of Ornithine decarboxylase protein (ODC) was not affected by H. pylori infection, but was decreased in the presence of NS398.