MAP kinase-interacting serine/threonine-protein kinase 2 is an enzyme encoded by MKNK2 gene. It contains a conserved C-terminal ERK-interacting domain, a catalytic domain with homology to calcium/calmodulin-dependent family of kinases, and putative MAP kinase phosphorylation sites located within the T loop of the kinase domain. MNK2 binds tightly to growth factor-regulated MAP kinases, ERK1 and ERK2. ERK and p38 phosphorylate MNK2, which stimulates its in vitro kinase activity toward a substrate, eukaryotic initiation factor-4E (EIF4E). MNK2 (amino acid residues 72–385), which includes the kinase domain, is expressed in E. coli as a single, non-glycosylated polypeptide chain. It is well purified by affinity, ion exchange and gel filtration chromatographic techniques.