The MAPK pathway is a series of protein kinases that communicate signals from the cell surface to the DNA in the nucleus. It is typically activated by external stimuli such as growth factors, hormones, and environmental stressors. When the pathway is activated, a signal is transmitted through a cascade of phosphorylation events, which ultimately leads to changes in gene expression. This pathway is composed of several key players, including ERK (Extracellular Signal-Regulated Kinases), JNK (c-Jun N-terminal Kinases), and p38 MAPK. Each of these kinases has distinct roles and is activated by different stimuli.
