S1PR1 and cancer: The functional S1PR1 antagonist FTY720 (fingolimod) slows the growth of intracranial xenograft tumors in mice [20], enhances the cytotoxic effect of temozolomide and has strong antiproliferative effects on GBM cells used in clinical trials for different cancers, including GBM (Clinicaltrials.gov, NCT02490930).