SPHK1 and neoplasm: Several studies in vitro and in vivo (only preclinical) demonstrated that ABC294640, the SPHK2-specific inhibitor, is able to inhibit proliferation of cancer cells or tumors more effectively or similarly than agents targeting SPHK1, in several tumor models, including ovarian (214), multiple myeloma (215), lung (216), kidney (217), breast (218), prostate (219), and pancreatic cancers (220).