FIG 1.

Affinity and potency of BYM338 at inhibiting myostatin (Mst) and activin A (Act A) signaling in a Smad2/3 CAG-luciferase reporter gene assay. (A) Affinity of BYM338 for human ActRIIA (hActRIIA) and human ActRIIB (hActRIIB) determined by solution equilibrium titration. Shown are representative examples of the results from 4 or 5 independent experiments. (B) Myostatin- and activin A-induced dose-dependent increases in Smad2/3 activity were measured with a CAGA-luciferase reporter stably expressed in HEK293 cells. (C) The ActRII-dependent response was determined upon addition of myostatin (10 ng/ml) or activin A (10 ng/ml) in the presence of increasing concentrations of BYM338. Shown are means ± SEMs from 3 to 4 independent experiments. RGA, reporter gene assay; RLU, relative light units.