Cdc25 Phosphatase Inhibitors: ProductsCell division cycle 25A (CDC25A) and cell division cycle 25B (CDC25B) phosphatases remove inorganic phosphate groups covalently attached to tyrosine, serine and threonine residues in proteins. CDC25A and CDC25B are involved in checkpoint control of cell cycle progression. During the cell cycle, CDC25A activity is highest in S phase, while CDC25B activity is highest during the G2/M transition. One of their major substrates, the kinase CDC2, is activated by dephosphorylation. Overexpression of CDC25A and CDC25B in mammary carcinomas has been associated with a poor patient prognosis.