PML and Salmonella Infections: Further characterization of the putative PML-regulated genes induced during Salmonella infection or the effect of Salmonella on PML SUMOylation/multimerization will be required to fully understand the differences in PML-dependent sensitivity between Listeria and Salmonella. Interestingly, Shigella flexneri, in addition to its effect on the Ubc9 level, was shown to induce a two-fold increase in the number of PML NBs in HeLa cells, which was not observed during incubation with a non-invasive avirulent strain (22).