NGF and major depressive disorder: Besides MAPK and Akt signaling, Ngf-modulated miRs seem to preferentially target other neuronal relevant pathways such as axon guidance and regulation of actin cytoskeleton, focal adhesion and GAP junctions, glutamergic, dopaminergic, cholinergic, and GABA-ergic synapses, long-term depression, circadian rhythms, mental disorders, and AD (Tables 1, 2).