Moreover, the macrophages and dendritic cells (type of white blood cells) in these Salmonella-colonized tumors secrete IL-1β, a protein responsible for anti-tumor activity.[3] S. Typhimurium flagellin increases both innate and adaptive immunity (nonspecific and specific defense mechanisms) of the bacteria by stimulating NK cells (Natural Killer cells) to produce interferon-γ (IFN-γ), an important cytokine (regulatory protein) for this immunity.[2] Listeria inhibits tumors through NADPH oxidase mediated production (nicotinamide adenine dinucleotide phosphate oxidase) of ROS (reactive oxygen species) which is a cell signaling process that activates CD8+ T cells (cells that kill cancerous tissue) which target primary tumors.[4]