Recent studies have reported the deleterious physiological and metabolic changes in Mstn-/- mice including impaired force generation and susceptibility to contraction-induced injury. Such observations have raised the concerns about the functional quality of the increased muscle resulting from therapeutic blockade of Mstn. Here we provide proteomic evidence to demonstrate that therapeutic Mstn inhibition has minimal effects on muscle proteome composition whereas the genetic ablation of Mstn induces marked changes. Furthermore, this study also represents the first proteomic analysis of the pharmacological blockage of the Mstn/activin receptor pathway being actively pursued as a potential therapy for multiple muscle wasting disorders.