ACVR2B (activin A receptor type 2B) is a transmembrane serine/threonine kinase that serves as a primary receptor for activin ligands in the TGF-β superfamily signaling pathway. As the rate-limiting component of the activin receptor complex, ACVR2B binds activin-A and activin-B at the plasma membrane and phosphorylates downstream type-1 receptors (ACVR1, ACVR1B), which subsequently activate SMAD2/3 proteins for nuclear translocation and transcriptional regulation. Beyond canonical activin signaling, ACVR2B also antagonizes myostatin and serves as a direct binding target for other TGF-β ligands, including GDF3, which modulates adipose tissue lipolysis and insulin sensitivity 1. ACVR2B regulates diverse physiological processes including muscle development and regeneration—notably, DLK1 inhibits myostatin-ACVR2B signaling to promote myoblast differentiation 2—spermatogonial stem cell self-renewal 3, and immune homeostasis in tumor microenvironments 4. Pathologically, ACVR2B dysfunction associates with heterotaxy, congenital heart defects, and skeletal abnormalities 5. In ischemic stroke models, dysregulation of the circ_0000566/miR-18a-5p/ACVR2B axis promotes endothelial cell apoptosis and inflammation 6. Therapeutic targeting of myostatin-ACVR2B signaling shows promise for muscle wasting diseases, though clinical translation remains challenging 7.