A highly specific, cell-permeable inhibitor of p38 kinase (IC50 = 34 nM in vitro, 600 nM in cells). Also known as reactivating kinase (RK) and CSBP (cytokine synthesis anti-inflammatory drug binding protein). Does not significantly inhibit JNK or p42 MAP kinase even at 100 μM. Inhibits IL-1 and TNF-α production from LPS-stimulated human monocytes and the human monocyte cell line THP-1 (IC50 = 50-100 nM). SB 203580 has also been shown to be an effective inhibitor of inflammatory cytokine production in vivo in both mice and rats.
