SPHK1 and influenza: Influenza infection increases intracellular SphK1-S1P and SphK-activated signalling pathways such as (1) NF-kB and ERK and (2) MAPK and PI3K/AKT, which are necessary for viral protein synthesis, the amplification of progeny virus, and nuclear export and transport of viral ribonucleoprotein (RNP) complexes to facilitate the production of infectious viral particles, respectively [212,221].