Dual specificity mitogen-activated protein kinase kinase 5 is a dual specificity protein kinase that belongs to the MAP kinase kinase family. This kinase specifically interacts with and activates MAPK7/ERK5.

This kinase itself can be phosphorylated and activated by MAP3K3/MEKK3, as well as by atypical protein kinase C isoforms (aPKCs). The signal cascade mediated by this kinase is involved in growth factor stimulated cell proliferation and muscle cell differentiation. Four alternatively spliced transcript variants of this gene encoding distinct isoforms have been described.Expressed in many adult tissues. Abundant in heart and skeletal muscle.