Selective inhibitor of TGF-β type I receptor ALK5 kinase, type I activin/nodal receptor ALK4 and type I nodal receptor ALK7 (IC50 values are 12, 45 and 7.5 nM respectively). Blocks phosphorylation of Smad2 and inhibits TGF-β-induced epithelial-to-mesenchymal transition. Only weakly inhibits ALK-1, -2, -3, -6 and MAPK activity. More potent than SB 431542 (Cat.No. 1614). Inhibits differentiation of rat induced pluripotent stem cells (riPSCs) and increases clonal expansion efficiency. Helps maintain homogeneity and long-term in vitro self-renewal of human iPSCs.