NOD1 and infection: The augmented bactericidal activity observed in wild-type macrophages following a combined stimulation of LPS with Tri-DAP or MDP was totally abolished in TLR4-deficient macrophages and selectively lost in NOD1- and NOD2-deficient macrophages upon live gram-negative S. typhimurium (Figure 5A) or gram-positive S. aureus (Figure S3A) infection.