Extracellular signal-regulated kinase 3 (ERK3) is a serine/threonine protein kinase also known as mitogen-activated protein kinase 6 (MAPK6) and p97MAPK. Unlike ERK1 and ERK2, ERK3 lacks the phosphoacceptor sequence T-E-Y in its activation loop. This kinase also possesses a unique C-terminal extension that is missing in traditional MAPKs. Highly unstable, ERK3 is rapidly degraded following N-terminal ubiquitination.
ERK3 is involved in various cellular proliferation, differentiation, and cell cycle progression in response to a variety of extracellular signals making it useful for the study of processes like angiogenesis, neurogenesis and tumorigenesis. The activation of ERK by proinflammatory stimuli may play important roles in innate immune responses and autoimmunity.