SKI-178 is a potent SphK1 inhibitor (IC50 0.1-1.8 µM) that triggers prolonged mitosis and intrinsic apoptosis. This effect is mediated by sustained CDK1 activity, which phosphorylates Bcl-2 and Bcl-xL while degrading Mcl-1. It serves as a valuable chemical probe for studying sphingolipid signaling, cell cycle arrest, and apoptosis in cancer research models.