A–C) Downregulation of DNMT3A, NUMB, SNAP25, and GAP43 decreases axonal growth. qRT-PCR (A) and Western blot (B) analyses show that transfection of axons with siRNAs against DNMT3A, NUMB, SNAP25, and GAP43 significantly reduced mRNA (A) and protein (C) levels of DNMT3A, NUMB, SNAP25, and GAP43 in axons of DRG neurons under regular glucose condition. D, E) Representative images of distal axons (D) and quantitative data of axonal length over DIV3 to -5 (E) show that reduction of these proteins resulted in decreases of axonal growth compared to axons transfected by control siRNAs (n = 6 chambers/3 individual experiments/group). Scale bar, 10 μm. *P < 0.05.