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. Phosphorylated by BRSK1 in vitro. Phosphorylated by CHEK1, which inhibits the activity of this protein. Phosphorylation at Ser-349 by AURKA might locally participate in the control of the onset of mitosis. Phosphorylation by MELK at Ser-166 promotes localization to the centrosome and the spindle poles during mitosis. Phosphorylation at Ser-319 and Ser-370 by MAPK14 is required for binding to 14-3-3 proteins (By similarity). Belongs to the MPI phosphatase family.