Belongs to the protein-tyrosine phosphatase family. Non-receptor class dual specificity subfamily. Lacks the N-terminal tyrosine-protein phosphatase domain of the family. It is therefore most likely inactive. The predicted gene At4g18590 has been split into 3 genes: At4g18590, At4g18593 and At4g18596. The predicted gene At4g18590 has been split into 3 genes: At4g18590, At4g18593 and At4g18596.