Ceramide kinase (CerK; EC 2.7.1.138) is an enzyme that phosphorylates endogenous ceramides, a family of waxy lipid molecules composed of sphingosine and a fatty acid. Ceramides are found in high concentrations within the cell membrane of cells and are one of the component lipids that make up sphingomyelin, one of the major lipids in the lipid bilayer. CerK was cloned and categorized on the basis of homology as a subclass of the family of diacylglycerol kinase (DAGK), distinct from sphingosine kinases (SPHK). CerK bears a Pleckstrin Homology (PH) domain which is required for membrane binding in vitro, sub-cellular localization at membrane compartments, and enzymatic activity. NVP 231 (Axon 1600) potently and selectively inhibits the binding of ceramide to CerK, resulting in decreased levels of the endogenous bioactive lipid ceramide-1-phosphate (C1P), and increased levels of ceramide and reduced cell growth[1].