γC3 interacts with Axin1 in vivo and is required for normal Axin1 subcellular localization. A, Endogenous Axin1 co-immunoprecipitates with γ-Pcdhs from P21 control cortical lysates; comparatively little Axin1 is co-immunoprecipitated from cortical lysates of C3KO mice. Representative Western blot images of (B) cytoplasmic and (C) synaptic fraction preparations from P21 cortex. Quantification of Axin1 (D), CDC42 (E), and β-actin (F) intensity normalized to total protein from cytoplasmic and synaptic fractions from C3KO and control mice. Levels of all three proteins are significantly reduced in synaptic, but not cytoplasmic fractions. n = 6 animals per genotype. Unpaired t test; *p <0.05, ***p < 0.001; ns = not significant.