Hippocampal neurogenesis in the DG region, which gives rise to PROX1-positive excitatory granule neurons from SOX2-positive neural stem cells constantly throughout a lifetime [35], has an important role in learning and memory formation, and is known to be affected in neurodegenerative diseases such as Alzheimer's disease [36, 37]. This evidence concerns the gene SOX2 and neurodegenerative disease.