For co-IP analysis, total proteins from hippocampi of adult C57BL/6 mice or from primary neuronal culture of P0 mouse hippocampus (Song et al., 2002) were prepared in the RIPA buffer containing 10% glycerol, 1% nonylphenoxypolyethoxy ethanol (Nonidet P-40), 50 mM Tris-Cl (pH 7.5), 200 mM NaCl, 2 mM MgCl2, 0.2 mM Na3VO4, 1 μg/ml protease inhibitor cocktail, and 0.1 mM PMSF). Samples were immunoprecipitated with anti-KIAA1212 (Immuno-Biological Laboratories, Inc.) or anti-DISC1 (Santa Cruz) antibodies, and then subjected to Western Blot analysis. Blots were stripped and reblotted with the same antibodies used for their immunoprecipitation to ensure equal loading. For insulin stimulation experiments, 70 to 80% confluent HEK293 cells were transfected with respective expression constructs using calcium phosphate. One day after transfection, cells were serum starved overnight before the treatment with 100 nM insulin for 15 mins. Proteins were harvested and processed for Western Blot analysis. The following antibodies were used: anti-GST (1:5000, Santa Cruz), anti-6×His (1:1000, Cell Signaling), anti-KIAA1212 (1:50, Immuno-Biological Laboratories, Inc.), anti-phospho-KIAA1212 (1:50, Immuno-Biological Laboratories, Inc), anti-DISC1 (1:1000, Santa Cruz), anti-phospho-AKT at Ser473 (1:1000, Cell Signaling), anti-AKT (1:1000,
