CBLN1 and central nervous system cancer: Based on these premises, the aim of this study was to investigate in T98G glioma cells, which are wild type for phosphatase and tensin homolog (PTEN), the physiological switch-off signal of PI3K/AKT, the effect of extracellular S1P on Cer metabolism and traffic, and the effect of S1P on the cytotoxicity induced by treatments that promote Cer accumulation in the ER.