MAP kinase-activated protein kinase 5 (MAPKAPK5) is a member of the serine/threonine kinase family. In response to cellular stress and proinflammatory cytokines, MAPKAPK5 is activated through its phosphorylation by MAP kinases, including MAPK1/ERK, MAPK14/p38-alpha, and MAPK11/p38-beta. In vitro, MAPKAPK5 phosphorylates heat shock protein HSP27 at its physiologically relevant sites.