SPHK1 and ovarian cancer: Second, direct evaluation in ovarian cancer cell lines (in which endogenous levels of SPHK1 are nearly undetectable) of the effect of SPHK1 overexpression on several hallmarks of cancer growth, showed that cells with ectopic SPHK1 expression had a higher rate of migration and proliferated more rapidly than control transfected cells, confirming that SPHK1 could indeed promote tumorigenicity.