Has a dual specificity toward Ser/Thr and Tyr-containing proteins. Prevents biotic and abiotic stress responses, including ozone, oxidative stress and pathogen attacks; represses MAPK activities during hypersensitive response to limit the spread of the HR response after infection by necrotrophic pathogen such as Botrytis cinerea. May be also involved in ABA and salt responses. Dephosphorylates MPK3 and MPK6. H2O + O-phospho-L-tyrosyl-[protein] = L-tyrosyl-[protein] + phosphate H2O + O-phospho-L-seryl-[protein] = L-seryl-[protein] + phosphate H2O + O-phospho-L-threonyl-[protein] = L-threonyl-[protein] + phosphate Associates with MPK3 and MPK6. Interacts with MPK6 is promoted during HR-like responses triggered by fungal elicitors, whereas interaction with MPK3 in repressed. Upon fungal elicitation, relocalizes surrounding spherical structures that could correspond to epiplasts. Expressed in flowers, seedlings, roots, leaves, and seeds. Present in stomata and meristematic cells. In flowers, expressed in stigmatic papillae, anthers, pollen grains and floral abscission zones. As flowers mature, progressively restricted to the abscission zones and the septum of the siliques. During seed development Mainly detected in seeds endosperm layer until the fourth day after germination. In young seedlings, confined to the cotyledons. Later observed in roots, especially in vascular organs and at branching points of lateral roots. In adult leaves, particularly localized in vascular tissues and hydathodes; mostly present in both young and senescent leaves, tissues undergoing developmental transitions. Accumulates in response to stress conditions caused by abscisic acid (ABA) or salt treatment. Delayed wilting symptoms in response to Ralstonia solanacearum and, by contrast, acceleration of disease progression during Botrytis cinerea infection, suggesting that this phosphatase plays differential functions in biotrophic versus necrotrophic pathogen-induced responses. Prolonged MPK3 and MPK6 activation during ozone treatment. Belongs to the protein-tyrosine phosphatase family. Non-receptor class dual specificity subfamily.