EPO and anemia: While EPO has been clinically effective over the past two decades, certain anemias, including those caused by hemolysis and genetic bone marrow failure disorders like DBA, do not respond well to EPO treatment due to a scarcity and functional deficiency of erythroid progenitor cells.4,8 Newly approved drugs like HIF-PHD inhibitors and activin receptor ligand traps are dependent on the late erythroid progenitors for efficacy.45,46 Our understanding of the mechanisms driving BFU-E cells self-renewal and the development of drugs to enhance their proliferation remains incomplete.