Tyrosine protein phosphatase which functions as a dosage- dependent inducer of mitotic progression (PubMed:1836978, PubMed:20360007). Directly dephosphorylates CDK1 and stimulates its kinase activity (PubMed:20360007). Required for G2/M phases of the cell cycle progression and abscission during cytokinesis in a ECT2-dependent manner (PubMed:17332740). The three isoforms seem to have a different level of activity (PubMed:1836978). {ECO:0000269|PubMed:17332740, ECO:0000269|PubMed:1836978, ECO:0000269|PubMed:20360007}. This is the function of CDC25B (cell division cycle 25B, ENSG00000101224).