A similar argument we would use for the absence of IFN-b production by hepatocytes. Such cells are known to be severely infected by L. monocytogenes during the complete course of infection. Nevertheless, no significant signal was observed in the reporter mice from liver. The absence of a contribution of Kupffer cells was expected since such cells are known to only bind Listeria but are not directly infected [58] . IFN-b induction requires cytosolic residence of Listeria.