(A) IMCD3 cells expressing C-terminally EGFP-tagged Chimera J with the S352A or S352D mutations were analyzed by immunofluorescence with antibodies against EGFP (green), ARL13B (red) and γ-tubulin (γTub, magenta). DNA was stained with DAPI. Arrows indicate cilia. Scale bar, 5 μm. Serine-352 is the mouse HTR6 equivalent of human HTR6 Serine-350, shown to be a target of CDK5 phosphorylation (17). S352A and S352D are non-phosphorylatable and phosphomimetic S352 mutants, respectively. (A, B) Quantification of ciliary localization from (A). Data are mean ± SEM of n = 3 independent experiments per construct, in each of which at least 50 transfected-cell cilia were counted for each G protein-coupled receptor. No significant differences were found by one-way ANOVA.