Abstract
p38 mitogen-activated protein kinases are key mediators of environmental stress response and are promising targets for treatment of inflammatory diseases and cancer. Numerous efforts have led to the discovery of several potent inhibitors; however, so far no highly selective type-II inhibitors have been reported. We previously identified VPC-00628 as a potent and selective type-II inhibitor of p38α/β with few off-targets. Here we analyzed the chemical building blocks of VPC-00628 that played a key role in achieving potency and selectivity through targeting an inactive state of the kinases induced by a unique folded P-loop conformation. Using a rapid, systematic combinatorial synthetic approach, we identified compound