Even prior to the identification of TLR4 as the LPS sensor (1, 2), inbred mouse strains that exhibited LPS unresponsiveness (e.g., C3H/HeJ and C57BL/10ScN) (41, 42) also differed in susceptibility to dextran sodium sulfate (DSS)-induced colitis (43, 44). The gene discussed is TLR4; the disease is colitis.