Purity >95%. A 83-01 is an inhibitor of TGF-Beta type I receptor kinase (ALK5), activin type IB receptor (ALK4), and nodal type I receptor (ALK7) (IC50 s = 12, 45, and 7.5 nM, respectively). It blocks the phosphorylation of SMAD2/3 and inhibits TGF-Beta-induced epithelial-to-mesenchymal transition. It has little effect on bone morphogenic type I receptors, p38 mitogen-activated protein kinase, or ERK. A 83-01 has been used to reprogram fibroblasts into alternative lineages, including neural stem cells and cardiomyocytes.