SPHK1 and ovarian clear cell cancer: Furthermore, sphingosine kinase 1 (SK1) inhibitor, FTY720, has been indicated to dramatically attenuate tumor weight in ovarian cancer cell lines (A2780 and SKOV3ip1) xenograft models and a clear cell ovarian carcinoma (CCC) PDX model 91, as well as in cervical cancer PDX models 92, supporting FTY720 as a potential therapeutic agent for gynecologic cancers.