Hirata et al. (2007) analyzed the expression of genes and confirmed the results by evaluating protein expression to determine the neuroprotective mechanism of HBO, and the researchers found that Lpar1/Edg2 expression is significantly upregulated by HBO treatment. Upregulation of Lpar1/Edg2 expression plays an important neuroprotective role upon HBO treatment after ischemic brain injury (Hirata et al., 2007). Lpar1/Edg2 can prevent apoptosis of numerous neuronal cell types and glial cells after ischemia-reperfusion injury (Savitz et al., 2006). The gene discussed is LPAR1; the disease is brain injury.