Assemblies of proteins have important functions in cells. But because they are very small, their composition from subunits can only be determined indirectly or with extreme time-effort. Scientists are currently developing a novel microscopy technology for the direct detection of such individual subunits of protein complexes in the cell membrane of intact cells. The methodology is applied to investigate a protein complex acting as a calcium channel in the cell membrane. The channel plays an important role in prostate cancer.