SB-525334

SB-525334 is a potent and selective inhibitor of transforming growth factor-β receptor I (ALK5, TGF-βRI) (IC₅₀ = 14.3 nM); displays 4-fold less potency against ALK4 (IC₅₀ = 58.5 nM) and inactive as an inhibitor of ALK2, ALK3, and ALK6 (IC₅₀ > 10,000 nM). In cell-based assays, SB-525334 (1 µM) blocks TGF-β1-induced phosphorylation and nuclear translocation of Smad2/3 in renal proximal tubule cells and inhibits TGF-β1-induced increases in plasminogen activator inhibitor-1 (PAI-1) and procollagen α1(I) mRNA expression in A498 renal epithelial carcinoma cells.