Selective inhibitor of TGF-β signaling (IC50 = 0.85 μM); displays little or no inhibition of activin, Wnt or BMP signaling pathways. Induces proteasomal degradation of the TGF-β type II receptor. Inhibits TGF-β-induced mesoderm formation from mouse embryonic stem cells (ESCs) during early differentiation; selectively promotes the differentiation of ESCs to cardiomyocytes in vitro between days 3-5. Does not induce differentiation of vascular smooth muscle cells or endothelial cells. Purity 98%. MW (observed): 415.52