SPHK1 and neoplasm: Despite incomplete characterization of function and mechanism, in vitro and preclinical in vivo data document that the SPHK2-specific inhibitor ABC294640 has been shown to inhibit proliferation of tumor cells or tumors more effectively or similarly than agents that target SPHK1 in several tumor models, including ovarian[122], multiple myeloma[123], lung[124], kidney[58], breast[58,125], prostate[126], and pancreatic cancers[127].