SPHK2 and cancer: Several other modulators, such as the dual inhibitors of SPHK1 and SPHK2, N,N-dimethylsphingosine (DMS) and SKI-II, the SPHK2 antagonist opaganib (ABC294640), the S1PR1 and S1PR3 antagonist VPC23019, and the S1PR2 agonist CYM5520, have been extensively utilized in cancer treatment and research [58,74,75,76,77].