The conclusion that impaired stromal support contributes to the ineffective hematopoiesis and peripheral cytopenias observed in patients with MDS is further supported by the effects of ACE-011 (sotatercept), an activin receptor type IIA antagonist, which has been shown to be mediated via stromal cells and not directly by HSPCs [30]. This evidence concerns the gene ACVR2A and myelodysplastic syndrome.