Munc13-4/GM1 colocalization in PIP5Kγ-silenced cells. (A) shRNA-ctr, shRNA-PIP5Kα, and shRNA-PIP5Kγ YTS cells were labeled with Alexa Fluor 594–conjugated CTxB. After fixing and permeabilization, samples were stained with anti–Munc13-4 Ab, followed by Alexa Fluor 350–conjugated secondary Ab. Fluorescent microscopic analysis using the ApoTome system was performed, and representative images of isolated cells are shown as a single optical section. Colocalization of fluorescence signals was analyzed with AxioVision Version 4.6.3 software. Bar represents 10 μm. (B) Percentage of cells showing Munc13-4 and GM1 colocalization was analyzed on randomly acquired fields (n = 80 cells) of each population. Data from 3 independent experiments (means ± SD) are shown.