In contrast to conventional 2-D monolayers, our 3-D colon model was previously shown to respond to S. Typhimurium infection in key ways that reflect the infection process in vivo, including adherence, invasion, structural damage, cytokine production, and the lack of dependence on the SPI-1, SPI-2 and flagellar T3SS for Salmonella invasion [29], [30]. This evidence concerns the gene SPI1 and infection.