Tyrosine protein phosphatase which functions as a dosage-dependent inducer of mitotic progression. Required for G2/M phases of the cell cycle progression and abscission during cytokinesis in a ECT2-dependent manner. Directly dephosphorylates CDK1 and stimulates its kinase activity (By similarity). H2O + O-phospho-L-tyrosyl-[protein] = L-tyrosyl-[protein] + phosphate Stimulated by B-type cyclins. Interacts with MAPK14 and 14-3-3 proteins. Expressed predominantly in spleen, lung, heart, brain, intestine, and muscle. Detected at the one-cell stage followed by a decrease in signal intensity at the two-cell stage. Detectable at higher level in the four-cell stage and expressed through the eight-cell, 16-cell and morula stages. Maximal expression at the blastocyst stage. Phosphorylated by BRSK1 in vitro. Phosphorylated by CHEK1, which inhibits the activity of this protein. Phosphorylation at Ser-351 by AURKA might locally participate in the control of the onset of mitosis. Phosphorylation by MELK at Ser-167 promotes localization to the centrosome and the spindle poles during mitosis. Phosphorylation at Ser-321 and Ser-372 by MAPK14 is required for binding to 14-3-3 proteins (By similarity). Belongs to the MPI phosphatase family.