NFE2L2 and ischemia: Li et al. examined the effect of pre-conditioning with 70% helium in a rat model of neonatal hypoxia–ischemia and found significantly increased NO levels, as well as the elevated expression of some anti-oxidases (e.g., nuclear factor erythroid 2-related factor 2 [Nrf-2], HO-1 and superoxide dismutase-1 [SOD-1]), a reduced brain infarct size, and improved neurological function after helium pre-conditioning.