ID2 and infection: Intriguingly, AAV2-Id2 infection after injury in EH obviously facilitates axon regeneration (Figure 7B,C) and AAV2-S14D-Id2 or AAV2-Id2 with active Akt robustly enhanced axon regrowth (Figure 7D,E, Figure 7—figure supplement 1C,D), resulting in numerous axons entering the hippocampus after biocytin tracing.