Several lines of evidence support the conclusion that neuronal death induced by axotomy and trophic factor withdrawal can be apoptosis. In transgenic newborn mice, Bcl-2 overexpression ameliorates motor neuron death induced by facial nerve transection (205), sciatic nerve transection (88), or optic nerve transection (89). Inhibition of caspase-1 and caspase-2 blocks apoptosis of dorsal root and sympathetic ganglion neurons after nerve growth factor withdrawal (206,207), and inhibition of caspase activity protects axotomized retinal ganglion cells from death after optic nerve transection in adult rat (208). Inhibition of caspase-1 also arrests apoptosis of motor neurons in vitro induced by neurotrophin withdrawal and PCD of motor neurons in vivo during the period of naturally occurring cell death (209).