ACE-031 is a soluble protein comprising the type IIB activin receptor (ACVR2B) and the immunoglobulin G1-Fc (IgG1-Fc), and has been studied for its potential in binding and inactivating myostatin, a protein that hampers muscle cell growth. It has been examined during the course of various research studies involved in muscle-wasting disorders and neuromuscular conditions such as Duchenne Muscular Dystrophy (DMD), as well as certain cancers such as those of the prostate or colorectal regions and lipid storage and bone metabolism.