ALT Known factors that influence P. aeruginosa invasion and intracellular trafficking. Factors influencing P. aeruginosa to invade epithelial cells are listed in panel 1, Internalization (top left). Alternatively, factors that influence bacteria to remain extracellular are shown in panel 2, Extracellular (bottom left). Bacterial factors promoting survival within vacuoles are shown in panel 3, Vacuole residency. Should bacteria exit vacuoles, the subsequent elements influencing the trafficking of bacteria into the cytoplasm, and events such as spread, membrane bleb entry, intraepithelial pod formation, and egress, are shown in panels 4–8. Solid arrows differentiate steps where mechanisms have been identified. Dashed arrows indicate observations where mechanisms remain to be elucidated or investigated.