When these SUMO1 or SUMO3 overexpressing macrophages were challenged with S. aureus Newman and the quantity of viable intracellular bacteria was counted after 24-h post-infection, a clear decrease in the intracellular persistence rate of this strain was observed in SUMO1 or SUMO3 overexpressing RAW 264.7 cells, when compared to control macrophages expressing green fluorescent protein (GFP) (Fig. 4a). This evidence concerns the gene SUMO3 and infection.