Updated project metadata. The homeoprotein Msx1 and Msx2 involved in normal skeletal muscle development and also contribute to muscle defects if altered during development. Deciphering the downstream signaling networks of Msx1 and Msx2 in myoblasts differentiation will help us to understand the molecular events that contribute to muscle defects. The objective of this study was to evaluate the proteomics characteristics in Msx1 and Msx2 mediated myoblasts differentiation, using isobaric tags for the relative and absolute quantification labelling technique (iTRAQ). The results showed that 1535 proteins with quantitative information were obtained. Volcano plots illustrated, in undifferentiated stage, 32 common downstream regulatory proteins for Msx1 and Msx2, 39 specific regulatory proteins for Msx1, and 13 specific for Msx2. While, in differentiated stage, 17 common downstream regulatory proteins for Msx1 and Msx2, 10 specific regulatory proteins for Msx1, and 21 specific for Msx2. Gene ontology, KEGG pathway and protein-protein interaction networks analyses revealed these proteins primarily associated with Arginine and proline metabolism, Glycolysis/Gluconeogenesis, Fatty acid degradation, Metabolism of xenobiotics by cytochrome P450 and Apoptosis. In addition, our data shows Acta1 was probably a core of the downstream regulatory networks of Msx1 and Msx2 in skeletal muscle development. The findings will help us to understand the molecular roles of Msx1 and Msx2 during muscle development as well as regeneration, and to understand the molecular events that contribute to muscle defects.