
Mass spectrometry (MS) is a tool to estimate protein abundances in a sample. Due to complexity of the entire process, the resulting data are often noisy, with gaps and difficult to interpret. This is further muddled by a widespread use of only 3 replicates. Hence, a typical proteomics experiment gives us very little idea about properties of data, in particular about their technical and biological variability. To improve our understanding, I analysed multiple calibration MS runs carried out under the same conditions. This way, I obtained data sets of up to 100 replicates, a feat unheard of in proteomics. I will show general properties of protein abundances, their distribution and recommend tools for differential abundance between experimental conditions. I promise to be brief and show a lot of pretty pictures, so those of you who don't give a damn about proteomics and not totally bored.