RB-005 is a potent sphingosine kinase isoform 1 (SK1) inhibitor, which may serve as therapeutic agent for proliferative diseases, including hypertension. RB-005, (IC(50) = 3.6 μM), which also induced proteasomal degradation of SK1 in human pulmonary arterial smooth muscle cells.
K145 is inactive against SphK1 and other protein kinases. K145 induces cell apoptosis and has potently antitumor activity. K145 is a selective, substrate-competitive and orally active SphK2 inhibitor with an IC50 of 4.3 µM and a Ki of 6.4 µM.