One would like to believe that the basic cellular processes have already been deciphered and that research can now focus on the details. But even today, new fundamental principles are being discovered through the combination of modern methods. The nucleolus is a nuclear structure that was first described in the 1830s. In the 1960s it was recognized that ribosomes, the protein factories, are produced in this organelle. Researchers have known for some time that protein folding helpers, so-called chaperones, move into the nucleolus under certain circumstances. It has been suggested that this relocation is related to protein production. Now researchers from the Max Planck Institute (MPI) of Biochemistry have shown that the chaperones that move into the nucleolus are bound to stress-sensitive proteins.