SPHK1 and cancer: Currently, many cancer studies demonstrate that SPHK1/S1PRs inhibitors, such as MP-A08, SKI-I, SKI-II, FTY720, LCL146, LCL351, SLP7111228 and B5354c, are able to suppress cancer cell proliferation or apoptosis induction in breast cancer, bladder cancer, leukemia cells, and PCa [163,164,165].