Enzymology. A family of enzymes that play an important role in signal transduction and regulate cellular functions such as cell differentiation, cell proliferation, and cell death. MAPKs are serine-threonine protein kinases that are activated by diverse stimuli (e.g., growth factors, stress stimuli, cytokines, ultraviolet irradiation, heat shock, and osmotic shock) via protein kinase cascades. They are the final components of the cascades, activated by phosphorylation by mitogen-activated protein kinase kinases (MAPKKs) which in turn are activated by mitogen-activated protein kinase kinase kinases (MAPKKKs).
MAPKs are subdivided in extracellular signal-regulated kinases (ERKs), c-Jun N-terminal kinases (JNKs), and p38 mitogen activated protein kinases.