The protein encoded by this gene is a member of the MAP kinase family. MAP kinases act as an integration point for multiple biochemical signals; and are involved in a wide variety of cellular processes such as proliferation; differentiation; transcription regulation and development. This kinase is activated by various environmental stresses and proinflammatory cytokines. The activation requires its phosphorylation by MAP kinase kinases (MKKs); or its autophosphorylation triggered by the interaction of MAP3K7IP1/TAB1 protein with this kinase. The substrates of this kinase include transcription regulator ATF2; MEF2C; and MAX; cell cycle regulator CDC25B; and tumor suppressor p53; which suggest the roles of this kinase in stress related transcription and cell cycle regulation; as well as in genotoxic stress response. Four alternatively spliced transcript variants of this gene encoding distinct isoforms have been reported.