ARMS/Kidins220 is required for dendrite development in hippocampal neurons. A, Hippocampal neurons were transfected with pSUPER vector and ARMS shRNA at 3 DIV, and neuronal morphology was examined at 7 DIV (DIV 3 + 4). Scale bar, 50 μm. B, ARMS/Kidins220 was knocked down at 7 DIV, and the morphology of dendritic trees was investigated at 14 DIV (DIV 7 + 7). Scale bar, 50 μm. C, D, Sholl analysis of neurons transfected with pSUPER vector and ARMS shRNA shown in A and B, respectively. E, F, Measurement of dendrite number and length of ARMS/Kidins220 knock-down neurons at different stages. **p < 0.005, Student's t test. G, Hippocampal neurons transfected with pSUPER vector and ARMS shRNA (DIV 7 + 7) were stained with the dendritic marker MAP2. Scale bar, 50 μm. H, Sholl analysis of transfected neurons in G. I, Hippocampal neurons from wild-type and ARMS^+/− mice cultured at low density were stained with MAP2 antibody. The dendrite morphology of individual neurons was examined. Scale bar, 50 μm. J, Sholl analysis of neurons in I.