Figure 2. Anti-ACVR1 antibody–induced changes in hepcidin and iron levels are consistent with inhibition of WT ACVR1 and activation of ACVR1[R206H] in vivo.

(A and C) In WT mice (n = 8/group), anti-ACVR1 mAb 1 decreased serum hepcidin (A) and increased serum iron (C). (B and D) In FOP mice [Acvr1^{[R206H]FlEx/+}; GT(ROSA26)Sor^CreERT2/+, after tamoxifen] (n = 5–6/group), anti-ACVR1 mAb 1 increased serum hepcidin (B) and decreased serum iron (D). ***P < 0.001 by Student’s t test.