AMG 548 is a potent and selective inhibitor of p38α with IC50 values of 0.5, 3.6, 2600 and 4100 nM for p38α, p38β, p38γ and p38δ, respectively. P38 mitogen-activated protein kinase (p38) is a serine/threonine kinase and is responsive to a variety of cellular stresses including inflammatory cytokines, osmotic shock, ultraviolet light, lipopolysaccharides (LPS) and growth factors. P38α kinase involved in the biosynthesis of TNFα and IL-1β at the transcriptional and translational level . AMG 548 is a potent and selective p38α inhibitor. In the antagonistic enzyme fragment complementation (EFC) and β-catenin-driven luciferase (SuperTOPflash) reporter gene assays, AMG 548 inhibited Wnt/β-catenin signaling, which was due to cross-reactivity with another kinase. AMG 548 inhibited 17 kinases by more than 80%. In U2OS-EFC cells, AMG 548 inhibited CKIδ and CKIε, which played an important role in the activation of Wnt/b-catenin signaling. Also, the concentration of AMG 548 needed to inhibit CKIδ/ε in cells was closely approximate that required to inhibit Wnt/b-catenin signaling in the EFC and TOPflash assays, which suggested AMG 548 inhibited Wnt/b-catenin signaling mediated by the inhibition of CKIδ/ε .