HMOX1 and subarachnoid hemorrhage: A study investigating the effect on gene expression of cytoprotective heme oxygenase-1 (HO-1) in neurons after subarachnoid haemorrhage showed that Nrf2 levels increased ~4-fold at 12 hours, peaking at >4.5-fold at 24 hours, with HO-1 levels increased to >3-fold at 12 hours and peaking at >4.5-fold at 24 hours [61].