SPHK2 and cancer: This is of particular relevance given the recent development of a highly selective and well-characterized small molecule inhibitor of SphK2 (ABC294640) [14], [15] displaying significant anti-tumor activity for a variety of cancers [16], [17] and which is currently under evaluation in a Phase I clinical trial for patients with solid tumors (Clinicaltrials.gov Identifier: NCT01488513).