SPHK1 and infection: Levels of the pro-inflammatory cytokines interleukin-6 (IL-6, Figure 4A–C), tumor necrosis factor-alpha (TNF-α, Figure 4D–F) and monocyte chemoattractant protein-1 (MCP-1, Figure 4G–I) peaked 6 h post infection in wt mice, while SphK1−/− mice showed a delayed onset of the pro-inflammatory cytokine response with highest levels 24 h post infection.