TABLE 1

SMAD 2/3 binding element functional assessment and heparin-binding activities of recombinant follistatin proteins

Protein	IC₅₀ Activin A	IC₅₀ GDF8	[NaCl] for Main Peak Elution from Heparin Sepharose
	nM	nM	M
FST315	2.2	10.8	0.65
FST-Fc	0.35	0.60	0.65
FST-ΔHBS-Fc	0.31	0.67	0.12

GDF, growth differentiation factor; FST-Fc, follistatin 315 murine IgG₁ Fc fusion; FST-ΔHBS-Fc, follistatin 315 heparan sulfate binding deficient mutant murine IgG₁ Fc fusion; FST315, human follistatin 315 isoform.