CREB1 and brain ischemia: Presently, a variety of signaling pathways have been implicated in the regulation of nerve regeneration after cerebral ischemia injury, such as cAMP-PKA-CREB signaling, the Notch pathway and the nitric oxide (NO) system, CPG15 gene, MOP receptor protein, GPR40 receptor protein, and the canonical Wnt pathway that involves β-catenin.