C-6 ceramide is a cell-permeable analog of naturally occurring ceramides. With a longer carbon chain than C-2 ceramide, it is somewhat more hydrophobic, and may more closely mimic the effects of natural ceramides. C-6 ceramide mediates many diverse biological activities including apoptosis, activation of protein phosphatase 2A, and inhibition of the mitochondrial respiratory chain. It also enhances the expression of COX-2 in rat granulosa cells and stimulates the growth of bovine aortic smooth muscle cells. C-6 ceramide acts in neuronal axons to inhibit neurite growth.