NES and teratoma: They observed that treatment of embryoid body-derived cells with a ceramide analog called N-oleoyl serinol (S18) upon their transplantation into the mouse brain removed undifferentiated Oct4+/PAR-4+ cells through induction of ceramide-mediated apoptosis, enhanced the number of Nestin+ neural cells, and inhibited teratoma formation, as opposed to untreated transplants, which gave rise to several teratomas (Bieberich et al., 2004).