SB-431542 is a potent, specific TGF-β type I receptor (ALK5) inhibitor with IC50 of 94 nM.
SB-431542 also substantially inhibits ALK4 and 7, but not other ALKs.
SB-431542 efficiently inhibits the ability of activated ALK4, ALK5, and ALK7 to phosphorylate Smad2.
SB-431542 is a selective inhibitor of endogenous activin and TGF-beta signaling but has no effect on BMP signaling, and has no effect on components of the ERK, JNK, or p38 MAP kinase pathways.
