S1P is an important signalling molecule both inside and outside of the cell, where it binds to S1P-specific G-protein coupled receptors triggering a cascade of SL-dependent cellular events.16 Given its central role as a second messenger, changes in S1P homeostasis have been linked to diseases such as cancer and diabetes.218–222 The biological function and regulation (for example palmitoylation and phosphorylation) of the protein of S1P and SK is a large, complicated and intensively active area of current research.223 As such, these topics will not be discussed here. Here, MBTPS1 is linked to cancer.