This entry represents a family of proteins associated with bacterial type III secretion systems, which are injection machines for virulence factors into host cell cytoplasm. Characterized members of this protein family are known to be secreted and are described as invasins, including IpaC from Shigella flexneri and SipC from Salmonella typhimurium. Members may be referred to as invasins, pathogenicity island effectors, and cell invasion proteins.