MAPKAPK3 is closely related to MAPKAPK2 sharing 72% nucleotide and 75% amino acid identity. MAPKAPK3 is activated by growth inducers and stress stimulation of cells. In vitro studies demonstrated that ERK, p38 MAP kinase and Jun N-terminal kinase were all able to phosphorylate and activate this kinase, which suggested the role of MAPKAPK3 as an integrative element of signaling in both mitogen and stress responses.