Phosphorylation of CaMKIIβ at S315 regulates spine morphology of Purkinje cells. (A) Effects of phosphorylation state of CaMKIIβ at S315 on Purkinje cell dendritic spine morphology in cerebellar slice cultures. Cerebellar slices were subjected to biolistic transfection with the indicated plasmids, cultured for 4 d, and immunostained with anti-GFP (green) and HA (red) antibodies. Representative images of distal dendrites of Purkinje cells are shown. (Scale bar, 2 μm.) (B–D) Quantitative analysis of spine density (B), spine length (C), and spine head width (D) along the distal dendrites of EGFP+ Purkinje cells in A. ***P < 0.0001, one-way ANOVA with Dunnett’s multiple-comparison post hoc test compared with vector control. The numbers of neurons (B) or spines (C and D) are indicated in each graph.