Understanding the functioning of a living cell supposes to decipher the complex molecular mechanisms which underlie the various cellular activities. All the genes of an organism, or its genome, constitute a static and specific databank of this living being. From a unique genome, every cellular type of an organism is going to express a set of proteins, or proteome, which is going to vary according to the environment of the cells. As proteins constitute the final actors of the biological processes, their study may offer the most relevant vision of the functioning of a living cell.

In this part the specificity of proteomic approaches are discussed. Analytical strategies involving biological mass spectrometry are presented in association with liquid chromatography. Multidimensional analyses are introduced for complex mixture analysis and quantification. In conclusion specific technological developments towards the miniaturization, the integration and the automation of the analysis of samples available in very low amounts are introduced as the next step towards single cell proteomics.