Significantly increased phosphorylated SPHK1 in the co-cultured THP-1 cells and significantly increased S1P production in the co-culture medium were found but very low level of S1P was detected in the medium of THP-1 cells without co-culture (Fig. 6D), indicating that most S1P production was from the co-cultured lymphoma cells (HH cells or SU-DHL-4 cells). Here, SPHK1 is linked to lymphoma.