Increased level of S1P produced by SphK1 is related to the oncogenic effects regulated by S1P and this is correlated to high level of SphK1 in glioblastoma cell lines [159,160]; the inhibition of SphK1 have been shown to decrease xenografts and human glioblastoma cell growth [161]. Here, SPHK1 is linked to glioblastoma.