SMPD1 and infection: As a conserved mechanism of stress response to a variety of stimuli (e. g. radiation, heat, inflammation, infection), acid sphingomyelinase (ASM or sphingomyelin phosphodiesterase, SMPD; E.C. 3.1.4.12, OMIM 607608) catalyses the rapid breakdown of inert, membrane embedded sphingomyelin to the highly bioactive mediator ceramide [1, 2].