Redistribution of multimerin after treatment of endothelial cells with secretagogues. Cells were washed and resuspended in fresh, serum-free culture media before treatment with and without ionophore A23187. Nonpermeabilized (NP) and permeabilized (P) cells were labeled with antimultimerin (a and b), antimultimerin and anti–von Willebrand factor (e and f), or with antimultimerin and propidium iodide to visualize cell nuclei (c and d show the multimerin-labeled structures associated with cells that contained labeled nuclei). Standard immunofluorescent microscopy images of endothelial cells processed 30 (a-d) and 60 minutes (e and f) after treatment with buffer or ionophore illustrate the redistribution of multimerin in response to secretagogues (N indicates cell nuclei) and the different distributions of multimerin and von Willebrand factor associated with secretagogue-treated endothelial cells (e and f).