Protein kinase inhibitor. Cell permeable, specific inhibitor of p38 (SAPK2a). Inhibits p38 MAPK stimulation of MAPKAPK2 (IC.The concentrations of SB203580 required to block Akt phosphorylation (IC50= 3-5µM) are only approximately 10-fold higher than those required to inhibit p38 MAP kinase (IC50=0.3-0.5µM). These data define a new activity for this drug and suggest that extreme caution should be used when interpreting data when SB203580 has been used at concentrations above 1-2µM. Non-specific effects include inhibition of COX-1 and -2. Enhances clonal growth of skin epithelial progenitor cells and stimulates neural stem cell proliferation. Alternative Name: 4-(4-Fluorophenyl)-2-(4-methylsulfinylphenyl)-5-(4-pyridyl)1H-imidazole. Formula: C21H16N3FOS. MW: 377.4. CAS Number: 152121-47-6. Purity: ≥97% (HPLC). Appearance: White to off-white powder. Solubility: Soluble in DMSO (50mg/ml). Long Term Storage: -20°C