Signal transduction by the JNK group of MAP kinases

MAP kinases are evolutionarily conserved proteins that are activated by a protein kinase cascade, including a MAP kinase kinase kinase, which phosphorylates a MAP kinase kinase, which in turn activates the MAP kinase by phosphorylation on Thr and Tyr residues. The primary sequence surrounding these phosphorylation sites serves to distinguish three major groups of mammalian MAP kinases. These include the Ras-activated ERK MAP kinases, which are characterized by the sequence TEY and the two stress-activated MAP kinases: p38 with the sequence TGY, and the c-Jun NH2-terminal kinases (JNK) with the sequence TPY. This review will focus on the JNK group of MAP kinases.