TGFB1 and central nervous system cancer: Amyloid processing, neuroinflammation signaling pathway, axonal guidance signaling, role of NANOG in mammalian embryonic stem cell pluripotency, glioblastoma multiforme signaling, glioma invasiveness signaling, synaptogenesis signaling pathway, amyotrophic lateral sclerosis signaling, neuroprotective role of THOP1 in Alzheimer’s disease, and TGF-β signaling