C8 Ceramide (d18:1.8:0) is a cell-permeable analog of naturally occurring ceramides. Unlike C2 ceramide, it is metabolized within cells to generate natural ceramides, often causing a dramatic increase in cellular ceramide levels. For this reason, treatment of cells with C8 ceramide (d18:1.8:0) may more closely mimic the effects of ceramide elevation than does treatment with shorter chain ceramide analogs. C8 Ceramide (d18:1.8:0) likely mediates many diverse biological activities, as do natural ceramides. It promotes the differentiation of human keratinocytes and induces apoptosis of both human leukemia cells and the U937 cell line.