Phospho-p38 MAPK (Thr180/Tyr182) (D3F9) XP ® Rabbit mAb

p38 MAP kinase (MAPK), also called RK (1) or CSBP (2), is the mammalian orthologue of the yeast HOG kinase that participates in a signaling cascade controlling cellular responses to cytokines and stress (1-4). Four isoforms of p38 MAPK, p38α, β, γ (also known as Erk6 or SAPK3), and δ (also known as SAPK4) have been identified. Similar to the SAPK/JNK pathway, p38 MAPK is activated by a variety of cellular stresses, including osmotic shock, inflammatory cytokines, lipopolysaccharide (LPS), UV light, and growth factors (1-5). MKK3, MKK6, and SEK activate p38 MAPK by phosphorylation at Thr180 and Tyr182. Activated p38 MAPK has been shown to phosphorylate and activate MAPKAP kinase 2 (3) and to phosphorylate the transcription factors ATF-2 (5), Max (6), and MEF2 (5-8). SB203580 (4-(4-fluorophenyl)-2-(4-methylsulfinylphenyl)-5-(4-pyridyl)-imidazole) is a selective inhibitor of p38 MAPK. This compound inhibits the activation of MAPKAPK-2 by p38 MAPK and subsequent phosphorylation of HSP27 (9). SB203580 inhibits p38 MAPK catalytic activity by binding to the ATP-binding pocket, but does not inhibit phosphorylation of p38 MAPK by upstream kinases (10). 1.Rouse, J. et al. (1994) Cell 78, 1027-37. 2.Han, J. et al. (1994) Science 265, 808-11. 3.Lee, J.C. et al. (1994) Nature 372, 739-46. 4.Freshney, N.W. et al. (1994) Cell 78, 1039-49. 5.Raingeaud, J. et al. (1995) J Biol Chem 270, 7420-6. 6.Zervos, A.S. et al. (1995) Proc Natl Acad Sci U S A 92, 10531-4. 7.Zhao, M. et al. (1999) Mol Cell Biol 19, 21-30. 8.Yang, S.H. et al. (1999) Mol Cell Biol 19, 4028-38. 9.Cuenda, A. et al. (1995) FEBS Lett 364, 229-33. 10.Kumar, S. et al. (1999) Biochem Biophys Res Commun 263, 825-31.