The functional regeneration of damaged axons and severed connections in the mature central nervous system (CNS) remains a challenging goal of neurological research. Mature CNS neurons are refractory to axon regeneration for two major reasons, one, because the activity of cell-intrinsic mechanisms that drive axon growth during development is low – and often further suppressed after an injury – and two, because certain molecules that are part of mature extracellular matrix and myelin act as strong inhibitors of axon growth. Genetic removal of growth inhibitory molecules can increase axon sprouting, but is not sufficient to enable long-range axon growth. Since axon growth is robust during early developmental stages, it has long been hypothesized that mature injured neurons may be “reprogrammed” to the earlier growth state by re-activation of the intracellular growth signaling cascades that drive axon elongation in the developing fetus.