SMPD1 and infection: CD95 ligands and cytokines such as tumor necrosis factor-α, interleukin-1 and interferon-γ but also other stimuli including oxidative stress, reactive oxygen and nitrogen species, ionizing radiation, UV-C radiation, heat shock and other agents of stress, injury or infections by HIV or bacteria have been shown to stimulate ceramide production [2]–[7], assumed to be in part due to increased ASM activity.