ACE‑031 acts as a soluble decoy receptor that binds and neutralizes Myostatin (GDF‑8), Activin A & B, GDF‑11, and BMP9 & BMP10. These ligands normally activate ActRIIB on muscle cells, triggering Smad2/3 signaling that suppresses muscle growth. ACE‑031 blocks this interaction, promoting muscle hypertrophy.