A-192621 is a potent, nonpeptide, orally active and selective endothelin B (ETB) receptor antagonist with an IC50 of 4.5 nM and a Ki of 8.8 nM. A-192621 promotes apoptosis in PASMCs and it also causes elevation of arterial blood pressure and an elevation
TAS05567 is a potent, highly selective, and ATP-competitive Syk inhibitor (IC50: 0.37 nM). TAS05567 only shows >70% inhibition of Syk and 4 other kinases (FLT3, JAK2, KDR, and RET with IC50s of 10 nM, 4.8 nM, 600 nM, and 29 nM, respectively) in a panel of 192 kinases.