TGFB1 and juvenile Huntington disease: 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, TGF-β signaling, Parkinson’s signaling, synaptic long-term potentiation, dopamine receptor signaling, dopamine degradation, and Huntington’s disease signaling