Rescue of KLF9-mediated neurite growth suppression by Dusp14 siRNA and PTP inhibitor IV. (A, B) At P0, control-transfected RGCs with no Dusp14 protein expression showed no effect when two different siRNAs against Dusp14 were transfected, in contrast to RGCs expressing higher levels of Dusp14 protein at P8, in which Dusp14 siRNAs significantly promoted neurite elongation. When overexpressing KLF9, siRNAs against Dusp14 rescued RGCs neurite growth at P0 (A) and P8 (B). (C, D) Similarly, AAV2 shRNA anti-luciferase (control shRNA) or AAV2 anti-Dusp14 (Dusp14 shRNA) were expressed in P8 RGCs. Dusp14 shRNA led to a significant increase in RGCs neurite growth. Images show staining against β-III-tubulin. Positively transduced RGCs were identified by a GFP reporter (C). Quantification showed significant increase in neurite growth after 5 days in culture (D). (E, F) PTP inhibitor IV (Dusp14 inhibitor) rescued KLF9-induced neurite suppression at P0 (E) and P8 (F), and promoted neurite growth in control-transfected RGCs at P8 (F), in dose-dependent fashion (*P < 0.05, **P < 0.01, paired t-test). Scale bar: 200 μm in (C). Error bars: SEM.