4% paraformaldehyde, 4% sucrose for 15 minutes at room temperature. Immunohistochemistry: Cells were then permeabilized in 0.1% Triton X-100/0.1% Na-Citrate/PBS for 3 minutes at room temperature and washed three times for 5 minutes with PBS. Cells were next blocked in 10% FBS/PBS for 1 hour at room temperature and incubated with primary antibodies in blocking solution overnight at 4 °C. The following day cells were washed 3 times in PBS for 5 minutes at room temperature. Then cells were incubated with secondary antibodies for 90 minutes at room temperature and washed 4 times in PBS for 5 minutes. Antibodies used were: KCNAB2 antibody (Proteintech; 1:100), MAP2 (1:1000, Millipore), Cy3 (1:500, Thermo Fisher Scientific), DAPI (1:100, Thermo Fisher Scientific), Alexa Fluor 488 Phalloidin (1:500, Thermo Fisher Scientific). Coverslips were dipped in demineralized H2O and mounted using MP Biomedicals immuno-fluore mounting medium. Confocal images were acquired using LSM700 or LSM710 confocal laser-scanning upright microscopes (Zeiss) with 10X, 40X (water) or 63X (oil) objectives. The zoom was set between 1× and 2× according to the cell size, with a pinhole of 34 μm and a speed of 1.58 μs per pixel. The confocal laser intensity was set to 2 and the gain was
