Activates the Jnk signaling pathway. Dephosphorylates and deactivates p38 and stress-activated protein kinase/c-Jun N-terminal kinase (SAPK/JNK) (By similarity). 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 Belongs to the protein-tyrosine phosphatase family. Non-receptor class dual specificity subfamily.