Figure 2: The ubiquitin-proteasome system in regulation of neural morphogenesis. Known signaling cascades for ubiquitin-dependent regulation of the formation of axons (bottom right inset), dendrites (left inset), and dendritic spines (top right inset). Regulatory factors depicted outside of the insets represent signaling from the cell body, rather than local regulation. E3 ligases are depicted in bold; arrows represent positive regulation; bars represent inhibition or degradation.