Recombinant Human Follistatin-related Gene Protein/FLRG (Catalog # 1288-F3) inhibits Recombinant Human/Mouse/Rat Activin A (Catalog # 338-AC) induced hemoglobin expression in the K562 human chronic myelogenous leukemia cell line in a dose-dependent manner (orange line), as measured by the psuedoperoxidase activity. Inhibition of Recombinant Human/Mouse/Rat Activin A (7.5 ng/mL) activity elicited by Recombinant Human Follistatin‑related Gene Protein/FLRG (0.1 µg/mL) is neutralized (green line) by increasing concentrations of Goat Anti-Human Follistatin-related Gene Protein/FLRG Antigen Affinity-purified Polyclonal Antibody (Catalog # AF1288). The ND50 is typically 1‑4 µg/mL.