Protein phosphatase which regulates actin filament dynamics. Dephosphorylates and activates the actin binding/depolymerizing factor cofilin, which subsequently binds to actin filaments and stimulates their disassembly. Required for completion of the gastrulation movement and for cytokinesis. 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 Interacts with actin and this stimulates phosphatase activity. Also localizes to the cleavage furrow and the midbody during cytokinesis. Maternally expressed in the early blastomere. Expressed in the involuting mesodermal cells and ectodermal cells of early gastrula stage embryos. Expression increases from stage 10.5, when the gastrulation movement occurs. Expression is concentrated at blastopore lips and the dorsal site of stage 11 embryos. Present in head structures and the trunk at the neurula and tailbud stages. Tyrosine phosphatase activity has not been demonstrated for this protein to date. Belongs to the protein-tyrosine phosphatase family.