A highly selective, potent and cell-permeable inhibitor of p38 MAP kinase. Binds within the ATP pocket of the active kinase (Kd = 38 nM, as measured in recombinant human p38), and selectively inhibits the p38α and β isoforms (IC50 = 50 and 100 nM at SAPK2a/p38 and SAPK2b/p38β2 respectively). Promotes stability of naive human pluripotent stem cells in culture. Also available as part of the MAPK Inhibitor Tocriset?. Purity 99%. MW (observed): 331.35