PROK2 and brain injury: 20,21 One mechanism through which LIF might promote neuronal survival directly is by increasing levels of the antioxidant protein, superoxide dismutase 3 (SOD3).22,23 Interestingly, though, in our studies of neonatal hypoxic-ischemic brain injury, IN-LIF did not increase levels of SOD3.10 Prokineticin-2 (ProK2) is another neurotrophic molecule that could be promoting neuronal survival in IN-LIF Rx mice.