Potent and selective inhibitor of type I bone morphogenic protein (BMP) receptors (IC50 values are 1.1, 1.8, 6.4, 34.4, 220, 302 and 321 nM for ALK2, ALK1, ALK6, ALK3, ActRIIA, ALK4 and ALK5 respectively)
Reduces BMP4-induced Smad1/5/8 phosphorylation in vitro (IC50 = 100 nM) and induces dorsalization of zebrafish embryos.