dual specificity protein phosphatase 14 (DUSP14), also called mitogen-activated protein kinase (MAPK) phosphatase 6 (MKP-6) or MKP-1-like protein tyrosine phosphatase (MKP-L), functions as a protein-serine/threonine phosphatase (EC 3.1.3.16) and a protein-tyrosine-phosphatase (EC 3.1.3.48). It deactivates its MAPK substrates by dephosphorylating the threonine and tyrosine residues in the conserved Thr-Xaa-Tyr motif residing in their activation sites. DUSP14 is an atypical DUSP; it contains the catalytic dual specificity phosphatase domain but lacks the N-terminal Cdc25/rhodanese-like domain that is present in typical DUSPs or MKPs. DUSP14 dephosphorylates JNK, ERK, and p38 in vitro. It also directly interacts and dephosphorylates TGF-beta-activated kinase 1 (TAK1)-binding protein 1 (TAB1) in T cells, and negatively regulates TCR signaling and immune responses.