C-2 ceramide is a cell-permeable analog of naturally occurring ceramides. It mediates many diverse biological activities, as do natural ceramides. These processes include differentiation of HL-60 cells, induction of apoptosis, activation of protein phosphatase 2A, and inhibition of the mitochondrial respiratory chain. C-2 ceramide also enhances the expression of COX-2 in human dermal fibroblasts and stimulates the growth of bovine aortic smooth muscle cells. The ability of C-2 ceramide to destabilize membranes may be responsible for its inhibition of platelet aggregation.