Illustration of the main pathways that control developmental axon pruning and axon degeneration by dying back, see text for details. Blue, red and purple text – genes and pathways involved in dying back neurodegeneration (blue), developmental neuronal remodeling (red) or both (purple). MT-Microtubules, Ub-Ubiquitin, UPS-Ubiquitin Proteasome System, TGFβ - Transforming growth factor-β, ESCRT -The endosomal sorting complexes required for transport, Caspases - cysteine-aspartic proteases or cysteine-dependent aspartate-directed proteases.