Protein phosphatase which antagonizes mitotic cyclin- dependent kinase cdc2; the inactivation of which is essential for exit from mitosis. To access its substrates; is released from nucleolar sequestration during mitosis. Plays an essential in coordinating the nuclear division cycle with cytokinesis through the cytokinesis checkpoint. Involved in chromosome segregation; where it is required for meiosis I spindle dissambly as well as for establishing two consecutive chromosome segregation phases. Allows damaged actomyosin rings to be maintained to facilitate completion of cell division in response to minor perturbation of the cell division machinery. Dephosphorylates the mitotic inducer cdc25 for its rapid degradation. Down-regulation of cdc25 activity ensures a prompt inactivation of mitotic cdc2 complexes to trigger cell division. Dephosphorylates also cdc2-phosphorylated nsk1; allowing nsk1-binding to kinetochores and spindle. Dephosphorylates ase1; which is essential for spindle midzone assembly and for continuous extension of the anaphase spindle. Tethered to the contractile ring by mid1; where it dephosphorylates cdc15. {ECO:0000269|PubMed:11448769; ECO:0000269|PubMed:11683392; ECO:0000269|PubMed:15128870; ECO:0000269|PubMed:15265986; ECO:0000269|PubMed:15525536; ECO:0000269|PubMed:16085490; ECO:0000269|PubMed:17562791; ECO:0000269|PubMed:18378776; ECO:0000269|PubMed:19570910; ECO:0000269|PubMed:22065639; ECO:0000269|PubMed:22624651}.