Mitogen-Activated Protein Kinases

Definition The Mitogen-Activated Protein Kinase (MAPK) pathway is a chain of proteins in the cell that communicates a signal from a receptor on the surface to the DNA in the nucleus of the cell. MAPKs are a group of serine/threonine–specific protein kinases which regulate diverse cellular processes such as proliferation, differentiation, growth, ▶ inflammation, and ▶ apoptosis. They can be activated by many stimuli, but primarily by growth factors, inflammatory cytokines (e.g., TNFa, IL-1, -6), cellular stress, and phorbol esters. MAPKs are able to phosphorylate numerous proteins like transcription factors, for example, nuclear factor (NF)-kB or activator protein 1 (▶AP-1), cytoskeletal proteins, kinases, and other enzymes (Fig. 1).