Exchange of material and information at the level of individual cells requires transport and signaling at the level of the plasma membrane enclosing the cell. Studying mechanisms at such tiny dimensions presents researchers with enormous challenges. Recently, researchers wanted to determine the function and distribution of cholesterol, an important component of the membrane. So far, cholesterol can only be labeled to a very limited extent with fluorescent dyes, which can be visualized under the microscope without damaging the membrane. Researchers at the University of Münster (Germany) have now developed a method to circumvent these difficulties. They synthesized a new compound with properties similar to those of cholesterol, but which can be labeled with dyes and visualized in living cells. There, the compound realistically mimics the behaviour of natural cholesterol.