Mitogen-activated protein kinase (MAPK) cas-cades are key signaling modules downstream of receptors/sensors that perceive either endoge-nously produced stimuli such as peptide ligands and damage-associated molecular patterns(DAMPs) or exogenously originated stimuli such as pathogen/microbe-associated molecular patterns (P/MAMPs),pathogen-derived effec-tors,and environmental factors.In this review,we provide a historic view of plant MAPK re-search and summarize recent advances in the establishment of MAPK cascades as essential components in plant immunity,response to environmental stresses,and normal growth and development.Each tier of the MAPK cascades is encoded by a small gene family,and multi pie members can function redundantly in an MAPK cascade.Yet,they carry out a diverse array of biological functions in plants.How the signaling specificity is achieved has become an interesting topic of MAPK research.Future in-vestigations into the molecular mechanism(s)underlying the regulation of MAPK activation including the activation kinetics and magnitude in response to a stimulus,the spatiotemporal expression patterns of all the components in the signaling pathway,and functional character-ization of novel MAPK substrates are central to our understanding of MAPK functions and sig-naling specificity in plants.