The hydrochloride salt of a saturated derivative of sphingosine. As an inhibitor of protein kinase C (PKC), safingol competitively binds to the regulatory phorbol-binding domain of PKC, a kinase involved in tumorigenesis. This agent has been shown to act synergistically with other chemotherapeutic agents and may potentiate chemotherapy drug-induced apoptosis in vitro and in vivo. [ ]