FKBP51 is considered a risk factor for psychiatric disorders. However, for the first time, new research results have shown positive effects: Instead of making people anxious or impairing their ability to think, the protein can have the opposite effect and thus promote resilience. The effect it has depends on the type of cells in which it becomes active. Furthermore sex plays a decisive role: Female model animals reacted either fearfully or courageously to the protein, while males were cognitively weakened or strengthened. The results do not make the development of a blocking drug any easier. But they show all the more how important basic research and sex-specific studies are.