We observed that ΔospC3 Shigella is significantly attenuated in B6.Nlrc4–/– mice but not in B6.Nlrc4–/–Casp11–/–, indicating by a ‘genetics squared’ analysis (Persson and Vance, 2007) that Shigella effector OspC3 inhibits CASP11 during oral mouse infection (Figures 3 and 4). This evidence concerns the gene SCAF11 and infection.