MAPKs are part of a signaling cascade that begins with the activation of cell surface receptors by extracellular stimuli such as growth factors, cytokines, and stress. This activation leads to a series of phosphorylation events, ultimately activating MAPK pathways. There are three major MAPK pathways: the ERK1/2 pathway, the JNK pathway, and the p38 pathway. Each of these pathways has distinct functions but can also overlap in their roles.
