Human biology has now entered into a phase of post-genomics and it might not be an exaggeration to say that the major outcome of the human genome sequencing has finally been to open the way to the exploration of the proteome-proteomics. Proteins are the functional output of genes and there are two main expected outcomes from human proteomics. The first is to discover new molecular markers for early diagnosis and profiling of pathologies. The second is to decipher the intracellular signaling pathways leading to the initiation and progression of pathologies, for the identification of new targets and the development of innovative therapeutic strategies. This is clearly a promising challenge that this book explores through a series of ongoing experiences and projects representative of the new era in which biology and medicine have now entered.