The complexity of living things is driven, in large part, by the huge diversity of cell types. Since all cells of an organism share the same genes, the diversity of cells must come from the particular proteins that are expressed. Cells in the brain are generally divided into neurons and glia. Within these two categories, however, lies a large diversity of cell types that we are only beginning to discover. The diversity of cell types in brain and other tissues has recently been expanded by new techniques, like RNA-sequencing, that identify and measure the mRNAs present in a cell, the so-called transcriptome. Although mRNAs are the template for proteins, the transcriptome is a poor proxy for proteins that a cell actually makes, the proteome. Scientists from the Max Planck Institute for Brain Research in Frankfurt now developed new methods to detect real-time changes in the proteome.