UMPS and infection: The transcriptomics analyses of intracellular Salmonella indicated that during the early (4h), middle (8h), and late (12h) stages of infection in J774-A.1 macrophages and HeLa cells, the expression level of ompA is significantly upregulated (2 to 2.5 fold) in comparison with other major membrane porins such as ompC, ompD, and ompF [11,12].