Because of previous overwhelming evidence that heme oxygenase 1 (HO-1) is a critical cytoprotectant against heme protein- induced AKI [19]–[21], HO-1 protein levels were measured in additional 2 month and 12 month old mice that had not been subjected to glycerol injection (n, 3 each). The gene discussed is HMOX1; the disease is acute kidney injury.