NOS2 and infection: We also observed a significant induction of IL-6, GM-CSF and CCL2 by SH0165 infection in 3D4/21 cells, even higher than that induced by SNP treatment; however, this was largely inhibited by S-MET (Figure 3c), implying that NOS2-mediated NO production contributes to proinflammatory activation in alveolar macrophages during G. parasuis infection.