ACE-031, also known as Ramatercept, is a dimeric fusion protein that consists of a fragment of the human activin receptor IIB (ACVR2B) linked to the Fc region of human IgG1. Researchers primarily study ACE-031 for its potential to inhibit myostatin, a protein that negatively regulates muscle growth, making it a candidate for addressing muscle-wasting conditions such as Duchenne muscular dystrophy. Key findings from clinical studies suggest that while ACE-031 was generally well-tolerated and associated with increases in lean body mass and muscle volume, safety concerns led to the discontinuation of some trials. Current research status indicates that ACE-031 remains a focus of investigation, particularly in the context of its effects on muscle growth and metabolism, although it is not yet approved for clinical use and is often found in black market products.