Fig. 3.

Antagonist activities of peptides in Smad reporter assays. (A) Receptor activation by TGFβ, activin A, MSTN, or GDF11 was detected by Smad2/3 reporter assays. Receptor activation by BMP9 was detected by Smad1/5/8 reporter assays. Percent inhibition was calculated as described in the “Materials and methods” section. (B) Gene expression analysis of activin receptors in the HEK293T cells that were used in the Smad reporter assays. Target mRNA expressions were normalized to the expression of the internal control gene 36B4. (C) Ligand-binding activities of ActRIIB-Fc and ActRIIA-Fc as determined by plate ELISA.