It is worth pointing out one important fact, that is, whether HIF-1α is protective or detrimental in ischemic stroke depends on the stroke stage, ischemia severity and ischemia duration (Yang et al., 2013). For example, there are studies showing that HIF-1α knockdown protects the brain against ischemic damage (Helton et al., 2005). However, other studies have reported that inhibition of HIF-1α and HIF-2α is beneficial to the neurons in the very acute phase after ischemic stroke (Barteczek et al., 2017). Under our experimental conditions, HIF-1α may be more likely a good molecule in promoting neuronal cells to rapidly adapt hypoxic conditions. However, future experiments are needed to demonstrate this speculation.