(A and B) Hippocampal neurons were treated with DMSO or AKT inhibitor for 4 hr. Enlargement of boxed area is in right. Scale bar, 50 µm or 5 µm. Arrows indicates radixin positive filopodia at the axonal tip. Bar graph shows radixin positive filopodia numbers in the axon (H, left) and relative radixin or S14-phospho-Id2 signal in the growth cone (n = 18–32) (H, middle and right). Error bars, SEM; **p<0.005 versus DMSO treated cell. (C) Hippocampal neurons were transfected with si-radixin or si-scramble control at stage three and fixed after 48 hr. Representative image (upper) and quantification of growth cone size, number of filopodia, and intensity of radixin were shown as bar graphs. scale bar, 5 µm. *p<0.05, **p<0.005 versus control. (n=15~18) (D) Hippocampal neurons were transfected with si-radixin or si-scramble and GFP-Id2 (S14D) at stage three and fixed after 48 hr. Enlargement of growth cone was shown in inserted box and bar graphs show axon length and radixin signal intensity. Scale bar, 10 µm. *p<0.05, **p<0.005 versus control. (n=17~20) See also Figure 6—figure supplements 1–3.