Recently, proteomic analysis performed by using cell lysates of fibroblasts derived from three lethal (type II) and three non-lethal (type III) OI patients carrying glycine substitutions in either COL1A1 or COL1A2, revealed 17 differentially expressed proteins exerting key effects on ECM structure and organization, cell signaling, as well as cell and tissue development and differentiation. This evidence concerns the gene COL1A1 and osteogenesis imperfecta.