A synthetic bioactive sphingolipid; increases the amount delivered and toxicity of doxorubicin in cancerous but not non-cancerous cells when incorporated in the nanoliposomal membrane of nanoliposomal-doxorubicin; induces proliferation and cytokine production by splenocytes in vitro (100-1,000 ng/ml); activates NF-κB production in C6 glioma cells (10 μM)