Blocking extracellular S1P either with an anti-S1P antibody (Sphingomab) or by reducing S1P release from cells with siRNAs directed against S1P-specific transporter Spns2; provoked a significant reduction in HIF-1α protein expression in hypoxic cells lines such as PC-3, human lung cancer cell line A549 and U87 glioma cell line [94]. Here, MBTPS1 is linked to glioma.