Erk5 (Mitogen-activated protein kinase 7, Big mitogen-activated protein kinase 1) is a member of the MAPK superfamily implicated in the regulation numerous cellular processes including proliferation, differentiation, and survival. In neuronal cells, Erk5 is required for NGF-induced neurite outgrowth, neuronal homeostasis, and survival. Erk5 is thought to play a role in blood vessel integrity via maintenance of endothelial cell migration and barrier function.