Shigella uses a type III secretion system to invade host cell and to cause disease. Secretion control and insertion of a translocation pore into cell membrane are critical steps for pathogenesis and are tightly linked to the formation of the needle tip complex formed by the IpaB and IpaD proteins (Veenendaal et al., 2007). Surface localizations of IpaD and IpaB were monitored by FACS analysis according to the localization protocol for Pseudomonas aeruginosa homolog PcrV (Lee et al., 2010).