A 83-01 sodium salt is a potent inhibitor of TGF-β type I receptor ALK5 kinase, type I activin/nodal receptor ALK4 and type I nodal receptor ALK7, reduces the level of ALK-5-induced transcription with an IC50 of 12 nM in Mv1Lu cells, also blocks the ALK4-TD and ALK7-TD induced transcription with IC50s of 45 nM and 7.5 nM in R4-2 cells, and weakly suppresses that induced by constitutively active ALK-6, ALK-2, ALK-3, and ALK-1. A 83-01 (0.03-10 µM) potently prevents the growth-inhibitory effects of TGF-β, and completely inhibits the effect at 3 µM. A 83-01 (1-10 µM) inhibits TGF-β-induced Smad activation in HaCaT cells. A 83-01 (1 µM) decreases cell motility, adhesion and invasion increased by TGF-β1 in HM-1 cells, but does not change cell proliferation.