Potent and selective p38α/β inhibitor (IC50 values are 26 and 102 nM, respectively). Exhibits >100-fold selectivity for p38α/β over 71 other kinases, enzymes and GPCRs, including p38γ, p38δ, JNK and ERK2. Inhibits LPS-induced TNFα production in U937 monocytes in vitro. Suppresses acute and chronic inflammatory responses in rat models of arthritis. Orally active. PH 797804 is the (-)-atropisomer, which is 100-fold more potent than its (+)-atropisomer. . Purity 98%. MW (observed): 477.3