IFNG and infection: Consistent with previous results demonstrating that IFN-γ inhibits the growth of Shigella in mouse embryonic fibroblasts44, we found that pretreatment of CT26 cells (a mouse colon carcinoma cell line) with IFN-γ for 16h resulted in substantially fewer cells harboring metabolically active Shigella 3h after infection (Fig. 1E, Fig. S1C).