HsClpX and HsClpP are differentially expressed in differenttissues. HsClpX is strongly expressed in skeletal and heartmuscles but less so in liver, brain, placenta, lung, kidney, andpancreas.7 Similarly, HsClpP is expressed at high levels inskeletal muscles, at intermediate levels in heart, liver, andpancreas, and at low levels in brain, placenta, lung, and kidney.