Ceramide: an intracellular mediator of apoptosis and growth suppression.

Ceramide is an endogenous lipid molecule generated by hydrolysis of membrane sphingomyelin, in response to cellular stimulation by hormones and cytokines. Ceramide appears to have a role in mediating biological responses in a wide variety of cell types. These responses are generally considered anti-proliferative, but endpoints are varied and include differentiation, growth inhibition, senescence and apoptotic cell death. Mechanisms for ceramide action involve regulation of protein phosphorylation via stimulation of a serine/threonine protein phosphatase, a proline-directed kinase and possibly other direct and/or indirect targets.