ACE-031 is a synthetic protein that belongs to the family of proteins known as growth differentiation factors (GDFs). It specifically inhibits the activity of myostatin, a protein that regulates muscle growth and development. By blocking the actions of myostatin, ACE 031 is thought to promote muscle growth and increase muscle mass.

Myostatin normally limits muscle growth by inhibiting the differentiation and proliferation of muscle cells. ACE 031, as an inhibitor of myostatin, is being investigated for its potential in treating conditions characterized by muscle wasting or weakness, such as muscular dystrophy. It has gained attention for its potential to enhance muscle development and strength.