Inhibitors of the MAP kinase p38 are potentially useful for the treatment of arthritis and osteoporosis. Several 2, 3-dichlorophenyl ureas were identified as small-molecule inhibitors of p38 by a combinatorial chemistry effort. Optimization for cellular potency led to the discovery of a new class of potent and selective p38 kinase inhibitors, exemplified by the 1- phenyl-5-pyrazolyl urea 7 (IC50= 13 nM).
