During the last years the heat shock response has been stu- died as a model system to analyze control mechanisms regula- ting the synthesis of heat shock proteins providing impor- tant general insight into the regulation of gene expression. But the major revelation, which has sparked interest from all quarters of biology, is the discovery that heat shock proteins play major roles in an extraordinary variety of normal cellular processes. They are the focus of investiga- tions in many areas of cell biology, including protein traf- ficking, signal transduction, DNS replication, transcrip- tion, protein synthesis, and in the assembly of di- verse protein structures. These aspects