S1PR1 and central nervous system cancer: A thorough analysis of Young and Van Brocklyn (2009) on the contribution of the single S1P receptors to glioma cell proliferation, migration and invasiveness by means of differential overexpression or RNAi knockdown of the receptors on glioma cell lines established that S1P1, S1P2 and S1P3 all contribute positively to S1P-stimulated glioma cell proliferation, with S1P1 being the major contributor.