Overexpression of p25 promotes microdomain switching in primary neurons. At 3 DIV, hippocampal neurons were transfected with human APP, syntaxin 1–HA, BACE1AA, and p25. At 6 DIV, patch formation was induced by mouse anti–human APPex, rat anti-HA, and rabbit anti-BACE1ex. (a) Coexpression of p25 caused a reduction of APP–syntaxin 1 copatching on axons. Copatching is indicated by arrowheads. Bar, 5 μm. (b) Quantification of copatching on axons demonstrates a cdk5-induced switching of microdomain association of APP in a similar way to N2a cells. Data are means + SD based on three independent experiments (n = 30–38). ***, P < 0.001.