As we previously reported that NMDA receptor subunits GluN1, GluN2A, and GluN2B show increased expression with time in cortical neurons in primary culture (Yamada et al., 2018), we examined changes in DNA methylation after NMDA-induced neuronal injury, which mimics cerebral ischemia-induced neuronal cell injury in vivo. Here, GRIN2A is linked to brain ischemia.