text: Mitogen-activated protein kinase (MAPK) networks can be found in eukaryotic cells. MAPK pathways in plants are known to regulate cell growth, cell development, cell death, and cell responses to environmental stimuli. Only a few of the MAPK mechanism components are known and have been studied. The components such as Arabidopsis MAPKKKs YODA, ANP2/ANP3, and MP3K6/MP3K7 functions in the development of the cell. MEKK1 and ANP1 function in the response to environmental stress. Unfortunately, only eight out of the twenty mitogen-activated protein kinases have been studied. The most commonly studied MAPKs are MPK3, MPK4, and MPK6, which are activated by a diversity of stimuli including abiotic stresses, pathogens, and oxidative stressors. MPK4 negatively regulates biotic stress signaling, while MPK3 and MPK6 function as positive mediators of defense responses. The plant has these positive and negative mediators allowing for normal plant growth and development, which has been proven true by the severely dwarfed phenotype of mpk4 and the embryo lethal phenotype of mpk3 and mpk6 mutants.