SPHK1 and ovarian neoplasm: Additionally, we injected parental ID8 cells, RAB27a−/− ID8 cells, SPHK1−/− ID8 cells, and SPHK1 ectopic expressing (EE) ID8 cells in the ovary of C57BL/6 mice to know the direct association of SPHK1 with the ovarian tumor growth.